Burning Question: Where Do Wheel Component Manufacturers Stand on Tire Inserts?
Trends come and go in the mountain bike world, and one of the items on that list seems to be declining are tire inserts. At one point it wasn’t uncommon to hear that most downhill racers, and occasionally even cross-country athletes, were using inserts in both the front and rear wheels.
They certainly caught on with claims of improving the lifespan of the wheel system by dispersing impact energy away from the rim and tire. In some cases, though, riders would even point towards the insert as the cause for a dead tire or wheel by pulling the tire off the rim, or the insert denting the rim itself. Inserts also don't directly protect the sidewall of the tire from being sliced either.
When Seb Stott asked in poll last year, the majority of readers said they didn't use inserts because they were heavy, costly, and to be fair, they're challenging to install and remove. Advancements in rim protection have been introduced as well, not to mention that some wheels now come with a “no questions asked” lifetime warranty so you may not be as concerned about breaking a wheel as you once were.
When I thought about what the insert offers a little further, I realized there are currently no brands out there that produce all three components of the system - the tire, insert, and rim. So I reached out to a few of the brands producing each of these components to understand what they believe are the best technologies and tactics for retaining air in your tires.
What components do you currently offer in the tire, wheel, or insert market?
DT Swiss offers complete wheelsets as well as rims. All of those products are engineered to work with the currently available tires. Those rims and wheels can all be used with a tube or tubeless setup.
What kind of technology or features do they offer in terms of holding air - be that tire stability, rim protection, resistance to denting/cracking/burping, flat prevention, sealing properties, spoke/rim strip protection, etc?
All DT Swiss rims are designed and produced to conform to the regulations of the ETRTO.
As well, all wheels/rims have their specific ASTM classification. This means that all those products will be engineered to withstand the specific loads for the intended use.
If it comes to our newest MTB family member the FR 541 rim for example, which is part of the SPLINE FR 1500 wheelset, is designed to be class leading when it comes to impact resistance as well as the specific design will help to avoid pinch flats.
In your experience, what combination best reduces the chance of losing air? Do you see tire inserts as a benefit or hindrance, or does it depend on the circumstances?
The most important thing if it comes to the tire/wheel system when we assume that high quality products will be combined and the product choice is the appropriate one to the area of application, is the correct tire pressure. This would be the best to avoid too much tire movement which may lead to an air loss.
Regarding tire inserts, first of all a tire insert is just alleviating the symptom but not the cause. So if you would like to protect your rim from impact, put more pressure in the tire! But there are reasons where an insert will be helpful. As some of the inserts will push the tire bead to the rim walls. This means that in case of an air loss the tire will not jump off the rim. This is for example the reason most of the World Cup XCO racers will use them, to have the chance to get to the feed zone fast, in case of a defect.
On the other hand a tire insert combined with very low pressure may help to prevent impact defects but will change the handling as well. So it would be cheaper and lighter to just higher the air pressure in the tire.
When designing a tire, rim, insert, or any combination of the three, do you take into account how a consumer might pair these options together?
When we start to develop a new rim we first of all consider the intended use and the expected forces when riding. This includes as well the forces of the tire. It’s easiest to predict the tire dimensions and the air pressure they will need. Next, we will take into consideration the available tires in the market. On the testing machines and in the real world, we will use tires from leading manufacturers and we are in contact with them for. Here, the ETRTO is the base of discussions as it regulates rims and tires regarding the dimensions which is already a good base.
How would a rim be best optimized for use with an insert?
At the moment we develop and engineer our rims to work best with high quality tires without inserts.
Why haven't we seen dedicated rims to deal with the additional forces of an insert?
There are rules for the rim/tire interface but there are no rules for inserts. Additionally I would like to mention this is not just true for bicycles but as well for any other tire/rim interface.
In an ideal world, what would be the best arrangement?
In an ideal world we would have dedicated rim/tire combinations with approved tire pressures like we see in the automotive world. This would lead to bombproof systems for a good driving performance. For those who would like to test around or try to beat times and winning races, they would need to find their own setup which might lead to defects as well.
What components do you currently offer in the tire, wheel, or insert market?
e*thirteen currently produces complete wheels, hubs, and rims, a range of tires, tubeless sealant, rim tape, and tubeless valves. We are toying with an insert now that will be raced by at least one World Cup DH/EDR team in 2024.
What kind of technology or features do they offer in terms of holding air - be that tire stability, rim protection, resistance to denting/cracking/burping, flat prevention, sealing properties, spoke/rim strip protection, etc?
There is a lot that goes into each facet of a tubeless wheel system, but the system relies on each part working well together. From what we have seen, there is no one major technology or feature that can create the perfect wheel system. It’s really a lot of small details that add up to significant improvements.
Our wheels are engineered to ensure that even when you have a bit of a wild ride and crack or dent a rim, the system won't fail, and you'll still be able to cross the finish line or ride back home safely.
Other small but significant improvements, such as slightly decreasing the tire well depth of the rim well on our Optimus trail wheels, makes tubeless setups much easier when using a lightweight trail tire.
Additionally, our rim tape is extremely flexible, making installation easy while the tape's width is based on the total profile length of the rim bed, ensuring full coverage and reliable sealing.
In your experience, what combination best reduces the chance of losing air? Do you see tire inserts as a benefit or hindrance, or does it depend on the circumstances?
For us, it is about having a system that lasts longer and consistently holds air through the life product. Each component plays a role in making that happen. First, the tape and valves need to be one hundred percent effective in preventing leaks. Second, the tire fit to the rim has to be right. Now that most rim and tire manufacturers are adhering to ETRTO, tire installation and seating of the bead are more consistent than in years past. At e*thirteen, we’re one of the few brands to make tires, rims, and tubeless components, so we have some unique insights as to how to get everything to fit and improve the rider experience.
The last part of the equation is the tire itself. Heavy-duty casings tend to have better air retention than lighter, single-ply tire carcasses. Tires are the part of the system with the most variability in the manufacturing process, so there are sometimes leaks or pinholes in the casing sidewalls. That’s why it’s important to select a sealant that not only seals punctures and small cuts at the tread but, on tire install, can migrate quickly to and seal any existing air leaks in the sidewalls.
When you add an insert to the system, the goals are usually to: 1) protect the rim and tire, 2) add lateral stability to the tire, 3) change the spring rate of the wheel-tire assembly, 4) reduce shocks transmitted to the rider.
So far, there isn’t an insert that does all of those things well at the same time, and most inserts can be extremely difficult to install. Our insert prototypes are configurable for achieving anywhere from two to four of the above goals while being easy to install and remove. We have a ways to go before finalizing the design and materials, but it will be a huge help to have it ridden and raced by some of the world’s best mountain bikers.
When designing a tire, rim, insert, or any combination of the three, do you take into account how a consumer might pair these options together?
Yes, but each part of the system also needs to stand on its own. The best compromises made can be difficult to hone in on, but we test internally as well as with our professional athletes in order to make those decisions.
How would a rim be best optimized for use with an insert?
First, it depends on the goal of the insert. Some inserts provide comfort and support, but according to a few of our World Cup teams, they are more likely to cause rim damage in some impact scenarios. The best thing to do is strength testing on rims with and without the insert to ensure there aren’t any unforeseen problems.
Why haven't we seen dedicated rims to deal with the additional forces of an insert?
For us, this is purely based on the fact that we need to produce wheels that perform with and without inserts. Long term, though, we are thinking about the wheel, tire, and insert that will work best as a system. Wouldn’t it be nice to completely eliminate pinch flats and dented or broken rims?
What drawbacks are there currently?
In terms of performance, we don’t feel there are drawbacks, but there are compromises to be made. For example, if you run a full-sized insert, you can run lower pressure with increased tire sidewall support and get a more damped ride feel, but the additional weight may be felt in certain riding situations, like on big jumps or manualing. Also, when using inserts, wheel handling may end up feeling less responsive.
Another compromise for riders is the ease of installation and service of wheels running tire inserts. Every rider is different and likes a variety of setups, but sometimes, the poor user experience of the installation will stop riders from getting the most out of their bikes. We don’t think this problem will be resolved as long as there isn’t a solution from a company that understands wheels, tires, and inserts as a single system. Eventually, this will happen, and a common solution will catch on in the industry. Tire inserts, especially on e-bike rear wheels, will likely become the norm as is mousse for moto. Remember when tubeless conversion used to be a nightmare for people? Now, it is pretty straightforward.
In an ideal world, what would be the best arrangement?
Our aim is to provide riders with the freedom to choose the equipment they prefer. The decision to select a particular wheel depends on your riding style and what you believe will give you an edge in performance. We want riders to have the option to choose the right wheel, set it up in the way that suits them best, and ensure we keep the air inside the tire, regardless of whether it is from e*thirteen or another brand.
What components do you currently offer in the tire, wheel, or insert market?
At Schwalbe, we’re 100% focused on bicycle tires and mainly concentrate on everything that might enhance the performance of them. So when we started working together with Stevie Smith around 12 years ago, we quickly found out that we needed some additional system in the tire to improve the reliability of both the tire and the rim, while enabling the rider to choose tire pressure freely without having to worry about snakebites or burping. This was the moment the Procore system was born. Instead of the foam inserts that are being used nowadays, Procore was a dual-chamber air system that consisted of a small diameter tube and tire that were inserted inside a conventional tubeless tire and pressurized to 60-80 psi. So if you like, Stevie basically paved the way for all current tire inserts back when he started winning on Procore.
What kind of technology or features do they offer in terms of holding air - be that tire stability, rim protection, resistance to denting/cracking/burping, flat prevention, sealing properties, spoke/rim strip protection, etc?
All of our Schwalbe Evolution Line tires are tubeless ready and compatible with all sealants currently available. Each rider can choose from a wide variety of carcass constructions that are all designed for their intended use, ranging from XC to DH with Super Race being the lightest and fastest casing for XC to Super DH which is our DH World Cup proven carcass construction.
Our Trail, Gravity and DH casing all come equipped with an Apex protection layer above the bead for improved sidewall stability and snakebite protection. Furthermore, they’re protected by a special anti-cut fabric on the sidewall called “SnakeSkin”.
In your experience, what combination best reduces the chance of losing air? Do you see tire inserts as a benefit or hindrance, or does it depend on the circumstances?
From our experience the best way to reduce the chance of losing air is an adequate choice of tires and wheels in a tubeless setup depending on the area of application and riding style. With good inserts you can surely increase puncture and burping protection to a certain extent, but based on our extensive tests we know that with clever use of material on the tire itself you can achieve a better ratio of puncture protection to weight. This has also lead to our teams drastically reducing the usage of inserts due to the addition weight, complexity but also issues that inserts introduce into the tire system. So in a nutshell, it is much more efficient to just choose a burlier tire that suits your riding.
When designing a tire, rim, insert, or any combination of the three, do you take into account how a consumer might pair these options together?
Absolutely. Only a tire that stays on the rim is a safe tire. Every tire we make goes through extensive testing in order to ensure that it fulfills our standards. The latter are primarily defined by the ETRTO committee, which Schwalbe has been a member of for many years, but we also have some additional internal safety standards.
To give you just one example, the blow-off safety in the norm says that a tire has to be able to withstand the indicated maximum pressure by 1,2 times for an hour. For our tests though, we ensure 1,6 times the maximum indicated pressure which is a huge safety benefit!
Other than that, we’re also involved into the development with most mayor wheel manufacturers and offer somewhat of an open-lab policy to check if their products are compatible with our tires prior to the launch in terms of safety, mounting and inflation properties. I think it’s fair to say that this has helped vastly to improve the tire-rim interface in the past couple of years.
How would a rim be best optimized for use with an insert?
There’re a few things that could be changed such as a widened flange for more compression surface or a strengthened rim well to deal with flat spots induced by stiff inserts. However, we’d actually prefer to leave this question to the rim manufacturers!
Why haven't we seen dedicated rims to deal with the additional forces of an insert?
Thinking back to why we even have inserts, it is mainly because of reliability issues with rims and tires. So instead of adjusting tires and rims to be able to withstand inserts, why not adjust them to the actual requirements of riders?
What drawbacks are there currently?
Because our Super Gravity or Super Downhill constructions have a high resistance against snakebites it can happen in the event of a heavy impact that the tire is fine, but the rim is damaged. Replacing rims is usually more expensive and time-consuming than a flat tire. On the other hand if you are riding a setup with an insert and you have a flat on the go it can be very frustrating to fix, because tires with proper inserts can be hard to dismount. On top of that, inserts introduce new issues such as flat spots or even increased burping! We’ve actually seen inserts acting like built-in tire levers and leading to premature tire blow-offs.
In an ideal world, what would be the best arrangement?
In an ideal world, it would be great if you could enjoy the respective advantages of all the different setups/systems without the associated disadvantages. That means an ideal arrangement would be the one that is simple, relatively cheap, durable, puncture resistant, lightweight and high performing.
What components do you currently offer in the tire, wheel, or insert market?
ENVE manufacturers mountain, road, and gravel wheelsets. Currently we are not in the tire or insert market. We do however offer a product and technology within our mountain wheels that provide some of the quoted rim and flat tire protection that inserts provide.
What kind of technology or features do they offer in terms of holding air - be that tire stability, rim protection, resistance to denting/cracking/burping, flat prevention, sealing properties, spoke/rim strip protection, etc?
ENVE has developed two technologies that improve the tubeless experience in terms of pinch-flat protection and tubeless performance/user experience:
1) Hookless beads – Probably seems obvious, but the main justification for hookless is tubeless performance. Hookless allows ENVE to manufacture rims using machined metal tooling that deliver consistent and precise bead seat diameter. A precise bead seat diameter ensures that the rims bead seat meets ETRTO specifications and that tubeless tires will seal appropriately on the established rim interface.
Wide Hookless Bead – ENVE introduced the Wide Hookless Bead (WHB) in 2016 with the M60 Plus (now called the M640). This was simply a concept that having a wider/blunter leading rim edge would be less harmful to soft rubber when compressed between the proverbial rock and a hard place. This technology is now featured on 100% of ENVE wheel models including road and gravel wheel models. This technology is scaled depending on use case. For example, a road wheel may only have a 3.5mm WHB, while a gravity focused mountain wheel features a 5mm WHB.
Protective Rim Strip (PRS) – This is truly novel and the reason it hasn’t been done by anyone else is simply because you have to design a rim to go with it. It’s also oddly expensive to produce. But this is a formulated polyurethane rim strip that both eliminates the need for tubeless tape, while also eliminating the possibility of full pinch flat. The plastic rim strips snaps onto the rim establishing the bead seat diameter, and wraps over the carbon hookless beads creating a barrier between the tire and the unforgiving carbon. When impacted, the PRS dissipates the energy and is soft enough that it cannot cut through the tire. The downside is that this technology is only available on an ENVE rim, and is therefore cost prohibitive for many riders. Many have asked if they can put the strip on a non-ENVE rim, but you cannot because you have to design the rim to the strip because of the dimensions critical to tubeless performance. Meaning, if you tried to put this strip on a non-ENVE rim it wouldn’t fit, but if it did happen to fit you wouldn’t be able to put a tire on it because the bead seat diameter would be well out of spec.
In your experience, what combination best reduces the chance of losing air? Do you see tire inserts as a benefit or hindrance, or does it depend on the circumstances?
Our Protective Rim Strip is hands down the best solution on the market for someone who doesn’t want to lose air. It’s a special race technology that our DH racers have come to love and trust. It essentially guarantees that even if you happen to crack a rim, the tire will not lose air pressure because the “air chamber” is isolated from the carbon rim. The absolute most bomber tubeless set up is an ENVE wheel with Protective Rim Strip (So M730 or M930) with a gravity/DH casing tire. Short of run flat ability, we have not found a justification for inserts. Because pinch-flats are the most common type of flat we have historically experienced, and given that our technologies have made pinch-flatting a very very rare occasion, we do not run inserts.
When designing a tire, rim, insert, or any combination of the three, do you take into account how a consumer might pair these options together?
We look at the monetary cost and performance cost of the wheel/tire/insert system. Obviously our rim protection/anti-pinch-flat technologies are baked into the rim design. We look at lifetime cost of the wheelset/tires. Tires aren’t cheap and while ENVE wheels are priced at the higher end of the market, our customers have cited lifetime savings based solely on the fact that they wear tires out now before they flat them. Most won’t go through 5-10 sets of tires a year, but that was a reality for some of our customers and athletes prior to the introduction of the Protective Rim Strip… At $50+ for a tire, it can add up.
From a performance perspective, there is the consideration of weight. We spend so much energy refining rim designs and laminates to strike the optimal balance between weight and strength for a specific application, it doesn’t sit right with ENVE to see people spending $2000 on a high-end wheelset to then go and add up to several 100 grams to the wheelset in inserts.
Why haven't we seen dedicated rims to deal with the additional forces of an insert?
This is an interesting question because it insinuate that inserts are potentially a contributor to rim damage or failures. Over the years, we have seen and experienced some rim breakages while running inserts that seemed inappropriate for the type of impact that was experienced. This coming from personal experience and anecdotal feedback from athletes. To design a rim for inserts, you must test and develop the rim with inserts.
What drawbacks are there currently?
What components do you currently offer in the tire, wheel, or insert market?
Wheels and rims.
What kind of technology or features do they offer in terms of holding air - be that tire stability, rim protection, resistance to denting/cracking/burping, flat prevention, sealing properties, spoke/rim strip protection, etc?
Our newest addition, the new Turbine wheelset, offers our Anvil Edge tire protection design. The rim edge is widened and shaped to help prevent pinch flats. Our wheels are designed with ride quality in mind – the intent here is for riders to be able to run wheels without an insert, feel the benefits of their tire and wheel system, and still see added flat protection.
In your experience, what combination best reduces the chance of losing air? Do you see tire inserts as a benefit or hindrance, or does it depend on the circumstances?
We definitely think tire inserts have their place. Many riders want to feel the exact ride qualities of the wheels and tires they are running, and want to omit an insert, which is where our rim technologies come in. At the same time, many hard hitting riders, or people that just want to have some additional security, won’t mind the added weight and added setup of an insert.
When designing a tire, rim, insert, or any combination of the three, do you take into account how a consumer might pair these options together?
We design our rims primarily around making tubeless setup as simple and secure as possible, while ensuring the strength and confidence inspiring ride properties of everything from our ARC rims to our new Turbine Wheels. As there are no ISO standards for inserts, we design for the tires and rim bead connection as our primary concern in this system
How would a rim be best optimized for use with an insert?
Our engineering team would prefer I don’t give anything away.
Why haven't we seen dedicated rims to deal with the additional forces of an insert?
Again, because there are no standards here, it would be challenging to identify exactly what to design for.
What drawbacks are there currently?
Just like rims dedicated to specific tires, rims dedicated to a specific insert design would likely be under one brand, limiting rider options to single system. Most riders don’t seem to keen on limited options.
In an ideal world, what would be the best arrangement?
We’re living in a pretty option-rich time, which feels like a boon. In a world where you can buy a wheelset (plug coming – like the Race Face Turbine) that dedicates it’s engineering work to tire protection and ride feel, it means that riders looking to run without an insert, their needs are met, and riders that still want that extra protection, there is little issue or hinderance to getting an insert in there anyway since the systems are designed to work that way. There is still room for innovation in these spaces, but it’s a pretty good time to be a mountain biker.
What components do you currently offer in the tire, wheel, or insert market?
Rimpact currently offers 5 insert models for a range of disciplines and also insert compatible valves to go along with them.
What kind of technology or features do they offer in terms of holding air - be that tire stability, rim protection, resistance to denting/cracking/burping, flat prevention, sealing properties, spoke/rim strip protection, etc?
Our inserts offer all of the above improvements thanks to different design features. By reducing the speed at which an impact takes place, impact forces are reduced and damage can be mitigated entirely, up to a point. Our Pro insert uses a very dense protection layer that sandwiches itself between the tire and rim hooks to increase this force mitigation even further. The shape of our inserts ensures the maximum material is situated between the bead and sidewalls of the tyre giving the tyre something to brace against when under high cornering forces. This limits burping and increases support through lessened deflection or sidewall 'roll' and a limited tendency for the inside bead to lift from the rim. Finally, the dense foam pressed against your side walls acts as a resonance damper and mutes the trail vibrations that pass through the sidewalls and into the rim, significantly smoothing out and quieting the bike on chattery terrain.
In your experience, what combination best reduces the chance of losing air? Do you see tire inserts as a benefit or hindrance, or does it depend on the circumstances?
The thickest tire, largest/most dense insert and highest air pressure will result in the least punctures. You can see that correlation in the testing Pinkbike conducted with Hunt Wheels here, and also in the multiple tests that can be found on our website as well as our competitors websites. We've also been approached by a couple of tire manufacturers who have independently conducted and concluded this same result, that with Rimpact inserts, a decrease in puncture chance is measurable and significant.
Obviously however, this setup is not ideal for an MTB use case. Riders and racers need a tire that provides traction, compliance and support simultaneously which means the upper limits of impact protection is intrinsically linked to the level of grip that rider can obtain. They also need a tire that is an appropriate weight for their discipline. A suitable analogy would be a "tire traits slider" or dial, where a rider can select where on the spectrum they want their tire to sit, between puncture proof and grip/control/weight. Whilst this is over simplified, turning the dial to maximum protection moves the slider further away from the grip end of the spectrum and moving it closer reduces the puncture protection performance. An insert effectively offers the rider an extra dial on this hypothetical spectrum, allowing them to control the grip level and the bottom out resistance of the tire independently, through pressure, tire and insert choice.
Whilst tire inserts aren't perfect, they offer benefits and performance increases that you cannot replicate with a traditional tire and tubeless set up on their own. There are no data points derived from our in house testing or from other independent tests, that we know of, that shows inserts to cause punctures. So when considering the specific question of, "What combination best reduces the chance of losing air?", the definitive answer is, a well designed insert, appropriate air pressure for the track, rider and conditions, and appropriate tire choice.
When designing a tire, rim, insert, or any combination of the three, do you take into account how a consumer might pair these options together?
Absolutely! The exact measurements, shape, stiffness and weight of an insert is linked to its performance and the performance of the whole system it is working within. We offer as many different sizes as we can to ensure each of the inserts fit as intended within a range of different rim and tire sizes available.
How would a rim be best optimized for use with an insert?
It's a bit of a chicken and egg scenario in that the insert is designed to be compatible with current rim designs and trends. If the trends change then we will modify or update our inserts to stay compatible and optimized. If we were to design something that requires a different rim design, then there wouldn't be any rims or customers with this newly designed rim to install it. There is a rabbit hole we could go down with completely redesigning the rim, insert and tire interface, but this means a new standard and I can already hear the furious typing coming from the comment section...
Why haven't we seen dedicated rims to deal with the additional forces of an insert?
By "additional forces", I assume you refer to this idea that some inserts seem to redirect forces into the middle of the rim and away from the stiff hooks, causing increased damage. Whilst we don't specifically subscribe to this idea holding any weight, our Rimpact Pro Insert has a unique two stage design, it's soft on the bottom and hard on top. This means the forces are dissipated through itself and through the strong rim hooks on the edges, rather than the softer rim bed. We have seen zero evidence or claims of our inserts causing stress to this central rim section in our testing, or in the years of selling them through customer feedback.
What drawbacks are there currently?
Everything has a drawback, there's no perfect product. A DH tire is often grippier, more resilient and supportive than a trail tire. But it comes with weight, price, installation difficulty and rolling resistance penalty. If we are talking about the drawback of inserts, there are a few. They cost money, have a mass, wear out, need to be installed etc etc. The good news is the best insert offerings add far more benefits than drawbacks and their benefits are so profound that they eclipse the drawbacks. When I go for a ride, I don't expect to get a puncture. It was a regular occurance before inserts. In fact I get them so rarely since using inserts that I am very surprised to get one at all nowadays and often ride without a pump, levers or tube, (don't be like me). I know my rear wheel weighs 100g more than if I didn't run an insert, but I'd also have more rim dents, more scrap tires, more wasted trail side repair time and also a slower bike due to lower tire performance.
In an ideal world, what would be the best arrangement?
It's a boring answer but an appropriate tire, rim and insert with appropriate pressures can't be beat! This dialed set up doesn't hold the rider back and limited issues will ruin a ride. I prefer reliability and peace of mind to charge as hard as I feel confident to, so I run either DH or Enduro tires and a combination of our Pro and Original inserts to find the perfect setup for me and my particular local trails.
What components do you currently offer in the tire, wheel, or insert market?
We create and produce wheelsets for every bike discipline (mtb, road, triathlon, gravel, track).
What kind of technology or features do they offer in terms of holding air - be that tire stability, rim protection, resistance to denting/cracking/burping, flat prevention, sealing properties, spoke/rim strip protection, etc?
Mavic pioneered tubeless back in 1999 in collaboration with Michelin and Hutchinson and introduced the Universal System Tubeless, an open license for tire and rim manufacturers to create a safe, easy, and efficient tubeless system on MTB rims.
The UST norm became official in 2019 in both world safety norms: ISO and ETRTO. The norm has been refined in 2021 and 2023 with the validation within the ISO and ETRTO norms. A wider central groove add-on to ease tire mount with wide tire beads and the no more hump locking the tire in place on the rim profile/bead will be validated in 2024.
Mavic introduced its Pinch Flat Protection (PFP) on its eBike rims since 2020. The rim aisles (walls) are machined to create an external shoulder and a wider contact surface on the top of the rim hooks (on the outside obviously). This wider surface created reduces by 20% the pinch flat/snake bites risk (less tire cuts)-see photos attached.
In your experience, what combination best reduces the chance of losing air? Do you see tire inserts as a benefit or hindrance, or does it depend on the circumstances?
Mostly circumstances: pressure, rider ability and riding technique level, speed, ground type, shock force.
When designing a tire, rim, insert, or any combination of the three, do you take into account how a consumer might pair these options together?
When designing a new rim, we do integrate the different use habits. For instance, on the new 2024 Deemax DH, the central groove has been enlarged (almost 2 times wider) to ease tire mount which casing, and beads are harder and wider too.
How would a rim be best optimized for use with an insert?
The pivotal aspect to take into consideration is to save enough air volume to keep getting the benefits of ride tubeless. It means keeping the ground grip, the rolling efficiency, and the riding precision. A too hard combination of tire/insert/pressure is impacting the performance of the complete system: less grip, more vibrations, less shock absorption, more muscle and material fatigue, shorter component lifetime, higher inertia meaning higher energy input to accelerate, etc.
Why haven't we seen dedicated rims to deal with the additional forces of an insert?
From both rim and tire manufacturer side everyone seems working on solutions without inserts like reinforced casing, PFP rim walls, etc. There are so many insert designs, density, volume, etc. existing that it is impossible to tell which is the best.
What drawbacks are there currently?
Most of the time it brings more difficulty to mount or put down the tire (even more with sealant and in the middle of a ride far from home) Some inserts can be pinched or compressed against the tire wall impacting badly the tire rolling efficiency. Or free floating inside the tire provoking noise, friction or move in the tire.
Inserts are not a 100% faultless anti-puncture solution. They also add weight and therefore inertia to the wheel.
In an ideal world, what would be the best arrangement?
Mastering the perfect design of both rim and tire but the tire pressure recommendations will always be an advice that has to be adapted to the riding conditions, bike, suspension settings, wheel, rider weight and skill.
A tubeless tire without sealant that would combine good rolling efficiency (thin casing) and puncture resistance (strong casing) - using a fully airtight rim without any rim tape (Fore drilling technology from Mavic) with the drilling of only the upper bridge of the rim profile. It is all about compromise on these criteria robustness/rolling efficiency/weight when coming to select the best combination. To conclude, those who are using tire inserts prioritize the resistance criteria over the weight/efficiency combo.
What components do you currently offer in the tire, wheel, or insert market?
We produce and manufacture carbon rims for mountain bikes in our Kamloops, BC facility.
What kind of technology or features do they offer in terms of holding air - be that tire stability, rim protection, resistance to denting/cracking/burping, flat prevention, sealing properties, spoke/rim strip protection, etc?
We design our rims with our proprietary hookless bead profile that seats easily but retains tires up to 60 psi with no problems. We also are using bleeding-edge carbon prepreg systems only available to North American customers that you can’t export overseas. We have a great relationship with our prepreg suppliers, and are constantly working on R&D projects to improve the fiber itself, as well as the resin system that holds it all together. These materials allow us to design rims that can take a serious beating while providing an unmatched ride feel and resisting fatigue - wear due to repeated use.
We also use relatively wide rim lips, 4-4.5mm for our enduro and DH rim offerings. We’ve found in our testing that this provides the best impact protection without excess weight, and greatly reduces the risk of snake-biting on the tire.
In your experience, what combination best reduces the chance of losing air? Do you see tire inserts as a benefit or hindrance, or does it depend on the circumstances?
We generally have found, in our experience, that running a few more PSI or a heavier casing will ultimately give you a more supported ride and impacts will be taken by the parts of the rims we have designed to take the hit.
In our team of in-house testers, nobody runs inserts. Those riders range from people who've picked up biking in the past year, all the way up to Canadian Enduro pro category podium finishers, from 120lb dirt jumpers to 220lb downhill animals. Johnny Helly, who raced the 2023 Enduro World Series U21 for us to great success, doesn't run inserts as well.
When designing a tire, rim, insert, or any combination of the three, do you take into account how a consumer might pair these options together?
In today's rim market, the buyer wants a rim that maximizes impact resistance without being too stiff or too heavy, and so all the weight typically added to strengthen the rim lip has to be clawed back out of an area of the rim that sees less load.
We're always going to recommend running a few more PSI or a heavier casing over an insert, but if you do want to run inserts, those that don't place a load on the center bead well are going to be our recommendation - Tannus and Huck Norris are both good options.
How would a rim be best optimized for use with an insert?
The rim wells would have to be designed to support pressure loads from the insert without severely affecting the weight or ride quality of the rim
Why haven't we seen dedicated rims to deal with the additional forces of an insert?
In our opinion, it’s because there still isn’t a firm grasp on exactly how an insert changes the loads on a rim. Without 100% understanding how an insert changes the distribution of impact loads, it’s difficult to properly reinforce those areas. Additionally, there will almost certainly be a weight penalty as a result of needing more material to help support these different loads.
What drawbacks are there currently?
Adding an insert to the rim does two things; 1) The internal volume of the rim is reduced, 2) Redirects loads from the rim lips into other parts of the rims.
For point 1, this is similar to a coil vs air shock - the coil won't have a mechanical "ramp up" at the end of it's stroke (save for shocks with HBO) like an air shock due to the increasing spring rate as the air compresses. Inserts are similar to this - the volume occupied by the insert takes away from air volume, meaning that 24 psi with an insert is very different from 24 psi without as the air is pressing on less space. Inserts are also essentially foam springs - the deformation is a linear relationship to the load applied. As you're taking away "progressive" volume from the air and replacing it with "linear" volume of the insert, the tire also isn't able to ramp up as much as the tire is "flattened" during an impact, which means you're more likely to actually put a sharp load on the rim itself without the support of a tire filled with only air.
For point 2, inserts which snap into the bead well transfer loads to that area of the rim. Under a heavy impact, as the tire-insert-air stack compresses and load is applied to the rim lip, the insert spreads/transfers that load from directly on the rim lips to the entire upper profile of the rim. What can happen in some cases is that while the ultimate load at the rim lip is reduced by the insert, those loads are now being transferred into that center well that is meant to support pressure loads rather than sharp impacts, which can lead to failures.
In an ideal world, what would be the best arrangement?
We've been working away hard in the test lab, and are learning a lot about inserts vs no inserts, but there's still work to be done to draw some concrete conclusions. For now, we still suggest a few more PSI/a heavier casing, or an insert that doesn’t interface with the center well like Huck Norris or Tannus.
What components do you currently offer in the tire, wheel, or insert market?
Tire inserts exclusively.
What kind of technology or features do they offer in terms of holding air - be that tire stability, rim protection, resistance to denting/cracking/burping, flat prevention, sealing properties, spoke/rim strip protection, etc?
People new to CushCore know it reduces pinch flats and protects the rim. Those benefits are important, but for me, CushCore is primarily about tire dynamics. It’s a way to tune how the tire flexes and responds as you ride.
An MTB tire is like a rubber ball filled with compressed air. It’s bouncy and springy, which is great for efficient rolling, but not so good for control and stability on a rough trail. Bouncy tires bounce off obstacles. They wiggle and flex, which can be unpredictable in corners.
Ideally, we’d like a tire that rolls like an XC tire but can corner and take hits like a DH tire. It’s both elastic and resilient, firm and controlled. With that in mind CushCore was designed to reduce: pinch flats, deflection off obstacles like roots and rocks, vibration transmitted to the rider, burping by anchoring the bead to the rim, and even reduce rolling resistance on bumpy terrain. CushCore also dissipates impact energy, adds rim protection, and improves cornering traction and control, all while allowing riders the option to switch to a lighter-casing tire.
In your experience, what combination best reduces the chance of losing air? Do you see tire inserts as a benefit or hindrance, or does it depend on the circumstances?
Optimizing for a single goal is easy. We could permanently eliminate flats by making a full-profile foam insert (like a motocross bib mousse). No air, no flats. We don’t make that product because of the performance compromise, for example rolling resistance would be unacceptable. It would feel like pedaling in sand.
If preventing flats is your only goal, run a sturdy rim, DH tire, and CushCore Pro.
CushCore reduces the risk of flats in any modern MTB rim and tire combo. It does not increase the risk of any common cause of tire failure.
When designing a tire, rim, insert, or any combination of the three, do you take into account how a consumer might pair these options together?
Definitely. Our model range is targeted by application (XC, Trail, Pro, E-MTB). It’s no accident this mirrors the categories offered by tire manufacturers. Each model is designed for an ideal fit with the rims and tires typical for that type of riding.
How would a rim be best optimized for use with an insert?
A wider rim flange helps reduce pinch flats – with or without an insert.
A rim with a reasonably deep rim well makes installation of the tire easier– with or without an insert.
For insert fitment, we consider the width between the tire beads when installed on the rim. Tire beads vary in width, so we have to consider the tire and rim combo. We want the insert under slight lateral preload when installed and inflated. Rims that are not unusually narrow or wide for a given application help us ensure insert preload is in the correct range.
Why haven't we seen dedicated rims to deal with the additional forces of an insert?
The idea that an insert can cause rim damage is a myth. A rim manufacturer brought this concern to our attention in 2019. Their rims were failing prematurely and thought CushCore a possible cause. They had not conducted any empirical testing.
We hired a third-party testing service (Wheel Energy Finland) to investigate. They tested several impact scenarios on carbon and aluminum rims, comparing tubeless setups with and without CushCore. Failure always occurred at higher impact energy with CushCore than without. CushCore increased rim durability in all tests.
What drawbacks are there currently?
We’re so used to the inherent compromises with the traditional tire and rim system. Pneumatic tires, as mentioned before, can have low rolling resistance but limited energy absorption. The air in your tires acts only as a spring, unlike your suspension which has an air spring and a speed sensitive damper. Additionally, the rim flanges create a location for a point load and are vulnerable to pinch flats and rim damage.
CushCore was designed to address these specific drawbacks of the traditional tire and rim combinations. While CushCore does add some weight, adding protection and a damper to the wheel system is well worth the performance gain.
In an ideal world, what would be the best arrangement?
A radical change in the performance of the wheel system has been ignored for decades. Current tire and rim manufacturers do not seem motivated to go beyond the existing standards. Due to high barriers to entry, there have been a limited number of startup tire companies offering something revolutionary for consumers.
Ultimately, we need a new standard for the rim-tire-insert interface. However, this is a huge project. It would involve significant product development and disrupt many of the industry’s largest manufacturers. The current design is entrenched as industry standard and adoption of a new technology would be a challenge in itself.
CushCore has succeeded in adding a true improvement to the traditional tire and rim system. There’s still room for development so we’re always considering what’s next.
What components do you currently offer in the tire, wheel, or insert market?
Roval makes XC, Trail and Enduro specific mountain bike wheels in both carbon and aluminum. Tires are available for every terrain and condition from XC race, Trail and full-on DH. Sealant and tubes are also offered to wrap up the entire package.
What kind of technology or features do they offer in terms of holding air - be that tire stability, rim protection, resistance to denting/cracking/burping, flat prevention, sealing properties, spoke/rim strip protection, etc?
Roval wheels: The best product family to talk about here is the new Traverse HD and Traverse SL II wheels we launched in July 2023. We took what we learned from Control SL and engineered multiple features into the Traverse rim shapes to give riders the best experience we could while addressing rider concerns about air retention:
1) Wide bead hooks: Both the Traverse HD and Traverse SL II rim shapes are designed with 5mm wide, flat top bead hooks on either side. This does a couple of things:
It creates a larger surface area, requiring 80% more force to pinch through the sidewall of a tire compared to our previous hook design. On Traverse Alloy, we refined the shape to prevent flat-spotting and to ensure that the bead hook dents inwards during impacts. When an alloy rim is made, you start with an aluminum bar that is then rolled into the final shape. That process changes the shape of the rim. We design the rolled shape. Outward denting is more likely to lose pressure because it releases the bead, so by designing the bead hook to dent inwards, the bead of the tire stays seated. Lastly, this beefy bead hook also contributes to the wheel’s overall impact strength to reduce cracking at the bead.
2) Rim diameter: When designing HD and SL II rim shapes, we made sure that, once the wheel is built, the tire and rim work together to ensure a proper fit for the best air retention; especially in high-energy situations like cornering. The shapes are also designed for floor-pump tubeless inflations and single-tire-lever install and removal.
3) Thread Bed Valve: The last feature, which is exclusive to our Traverse line right now, is our Thread Bed Valve. The design works with a threaded insert built into the rim at the valve hole. The valve then threads directly into the rim, torqued to 3Nm with a 5mm allen key. Rims, no matter carbon or aluminum, flex when under load. Even just sitting still. So, when you ride, the rim is flexing, compressing and expanding, almost similar to a lung. That causes compression nuts on standard valves to come loose over time because the rim’s movement creates space between the rim and the compression nut. By eliminating the compression nut from the system and threading the valve into the rim directly, we all but eliminate the risk of losing air at the valve hole. There’s also the added benefit that the nut doesn’t become glued to your rim from sealant (which I am sure many riders have experienced). Of course, if riders still want to use their own standard valve, those will fit just fine.
Specialized Tires: The interface between the rim and tire is extremely important. The tire’s molded bead shape and the rim well dimensions need to mate up just right, which ensures a seal for easily air up and retention. Using our in-house CT scanner, we can verify the best rim and tire interface under pressure, all within the dimension specs of ETRTO. Our Grid, Grid Trail and Grid Gravity casings have sidewall reinforcement, aiding in protection, support, and keeping the bead from twisting under high loads.
In your experience, what combination best reduces the chance of losing air? Do you see tire inserts as a benefit or hindrance, or does it depend on the circumstances?
Roval wheels: This is a complex question and answer because there are so many variables, and the types of riders out there are an incredibly broad spectrum. We have to start with what’s most important to the rider in any given scenario. Is it traction? Speed? Basic air retention and preventing burping? Protecting the rim at all costs? For a rider like me, 5’7’’ and 130 pounds, I rarely worry about air retention and instead prioritize traction as my most important variable. Then there is a rider at the opposite end of the spectrum. Someone like Brad Benedict, Specialized’s Senior Manager of Ride Dynamics, former World Cup DH rider, and pushing 200 pounds.
A couple of years ago, we asked Brad a specific question, “Can you ride your bike at full gas with no inhibitions or concerns that your equipment will fail?” His answer was, “No. Never.” Keeping in mind that Brad has access to all forms of wheel, tire, and insert technology and despite all of that, he still manages to rip tires off wheels. This was a clear indicator that the products available to riders fall short of rider’s performance potential. I think the reality is that different riders face different challenges and we have a lot of questions on the table and yet to answer.
Regarding inserts, we have started a deep dive into studying how rims, tires, and inserts work when energy is added to the system. We realize riders want options, so at this point our primary focus is ensuring our entire wheel and tire system are compatible with the current offering of tire inserts in the market while we continue to study the role inserts have as part of a complete system.
When designing a tire, rim, insert, or any combination of the three, do you take into account how a consumer might pair these options together?
Roval wheels: Absolutely. When developing rim shapes and wheel builds, we test using a wide range of tires and inserts to ensure they are compatible. We also CT-scan different combinations, conduct stiffness and energy tests on them, and do ample testing under real riders. Traverse and Control wheels are all approved to work with inserts, even with the new Traverse Thread Bed Valve.
Specialized Tires: Yes, a great example of this is when we designed the Cannibal tire. We spent an equal amount of time testing and tuning the Grid Gravity casing and apex profile using the most popular insert options, as well as without them. We tuned the tire stiffness and feel to be very consistent and compatible with either option. Our Gravity and Enduro riders run many different combinations, and tire consistency is key.
How would a rim be best optimized for use with an insert?
Roval wheels: From an engineering point of view, inserts can change load distribution under impact. Inserts also change the stiffness and energy of the tire system, which alters the impact energies a wheel sees during an impact. We definitely are working to understand these energies, like I said above. Do riders really need to spend $150 for inserts to protect their rim or hold their tire on? Our goal is to address the issues inserts set out to address through rim shapes and bead hook design, tire retention, and increasing impact strength, which makes for an overall lighter and ultimately more affordable system for riders. That’s where we are prioritizing our testing and development efforts.
Why haven't we seen dedicated rims to deal with the additional forces of an insert?
Roval wheels: As a brand, we don’t manufacture inserts. However, like I said above, it is our goal to completely understand how an insert interacts with the rim when energy is added to the system. The picture is being painted. We use our CT scanner and have created custom fixtures to exam deformation under load. We just haven’t created a way to do this while riding (but we are working on it). There are a lot of opinions out there regarding the cross sections of rims failing due to contact with the insert... but this is not something we have seen in Control and Traverse. What we really want to understand is exactly what happens when a 200lb rider cases a gap, mid-whip, and bottoms out the tire on the rim. Again, it’s more fun to ask, “how can we engineer a rim and tire combination that doesn’t require inserts in the first place?”
What drawbacks are there currently?
Roval wheels: The first and most obvious is weight. Riders take a weight penalty of 150g-290g per insert. They are also expensive at around $150 per set. The insert also creates a major performance change which, can be a good or bad thing depending on who you are as a rider. Instead of a gradual change to the system (tire size selection and air pressure adjustment, for example) the rider introduces a new variable to the system. Some riders describe this feel as “trail damping” or “ride quality.” But for some, this added spring in the system does the opposite. Again, it’s complex and depends on the individual rider.
In an ideal world, what would be the best arrangement?
Roval wheels: Would you smile if I said “We are working on it?”
Currently, there is no singular solution for every rider. However, there are solutions that give riders better options. Right now, with the products currently available, the best arrangement is finding the right wheel and tire compound/tread design/casing (and maybe insert) that suits the individual rider’s needs. We engineer our rims and tires to work seamlessly, while also ensuring our wheel and tire system is compatible with every kind of insert available, giving riders the widest range of options for what they feel is best.
I see a lot of riders out there running setups that don’t make any sense. For example, at the Cascade Dirt Cup Enduro in Bellingham, WA this last summer, I saw a rider with a set of Control SL’s (our XC wheelset), with Maxxis DHF/DHR single ply casings, and CushCore front and rear on his Forbidden Dreadnought. This rider took a 1240g XC race wheel and added 500g+ with inserts to protect against pinch flats. Now, he may have been trying to use a lighter tire with inserts to create a lower volume in the tire, but in my mind he may have been better served using a wheel intended for trail/enduro riding and a different tire casing or compound. Helping riders to better understand the tech that goes into their products is the big challenge. With a thousand combinations available, it’s not a surprise that so many riders face these issues we are discussing.
What components do you currently offer in the tire, wheel, or insert market?
Giant currently manufactures a range of own-brand mountain bike wheels that are both specced across our bike line as well as available after-market. Stand- out examples in the line-up are our lightweight carbon 30mm inner-width XCR cross-country wheels and our all-new super-durable carbon TRX trail wheels and aluminum TRA enduro wheels.
What kind of technology or features do they offer in terms of holding air - be that tire stability, rim protection, resistance to denting/cracking/burping, flat prevention, sealing properties, spoke/rim strip protection, etc?
Our all-new TRX carbon trail and TRA aluminum enduro wheels feature what we call “Wide Guard” technology which is a burly 5mm thick rim sidewall that broadens the contact point between the tire and the rim, significantly reducing the incidence of pinch flats. It also better protects the rim from damage that can occur with big impacts on sharp or square edges, all without sacrificing weight or wheel performance.
In your experience, what combination best reduces the chance of losing air? Do you see tire inserts as a benefit or hindrance, or does it depend on the circumstances?
Although tire inserts can still be an important part of a rider’s toolkit depending on the terrain and speed they’re riding, we believe that our Wide Guard rims really do away with the need for inserts for most riders on most trails. By removing heavy tire inserts and reducing unsprung weight, suspension performs better too.
When designing a tire, rim, insert, or any combination of the three, do you take into account how a consumer might pair these options together?
As I say, tire inserts can still play an important role depending on riding conditions, especially in competition. From our research and testing however, we feel that although inserts will add protection, they sacrifice weight and can also lead to imbalance, especially on the front tire, reducing efficiency as the rider fights to stabilize the bike. That’s why we’ve developed wheels with thick 5mm wide rim walls, to eliminate the need for inserts for most riders – lightening up their wheels, improving their suspension performance and increasing efficiency, all the while reducing the incidence of pinch flats and impact damage.
How would a rim be best optimized for use with an insert?
This really depends on the type and design of the inserts as well as the application of the wheel.
Why haven't we seen dedicated rims to deal with the additional forces of an insert?
Since we believe that most riders under most circumstances will benefit more from not having to run inserts, from our perspective, it was more interesting to develop a rim that could reduce pinch flats and withstand impact forces without the need for inserts.
What drawbacks are there currently?
As I’ve said, inserts add significant unsprung weight to the bike, which can affect suspension performance. Likewise, inserts can also pretty significantly affect tire performance and impact efficiency. They can also be tricky and time consuming to install.
In an ideal world, what would be the best arrangement?
There’s no real right answer here; under certain circumstances, especially with the speeds and terrain found on some World Cup tracks for example, inserts can offer riders an advantage, although last season our factory team rider Youn Deniaud raced and won on the aluminum TRA wheels with no inserts. In general, for most riders on most trails we believe that the wide 5mm rim walls of the TRA and TRX wheels provide the lightest and best-performing solution to avoiding pinch flats and impact damage.
What components do you currently offer in the tire, wheel, or insert market?
Hunt Bike Wheels offer an extensive range of complete wheelsets (both alloy and carbon fibre) along with rims for covering most different riding styles within cycling. All the products have been designed with a tubeless set up in mind.
What kind of technology or features do they offer in terms of holding air - be that tire stability, rim protection, resistance to denting/cracking/burping, flat prevention, sealing properties, spoke/rim strip protection, etc?
All of our products have been designed and manufactured to ensure the rim-tyre interface meets ETRTO standards. Part of the standard states a high sided 6+/-0.5mm flange for hookless rims and a 5.5+/-0.5mm sidewall with a R0.7mm hook for hooked rims is required to ensure the best seal (provided the tyre also meets the ETRTO standard and a good sealant is used).
Rim protection wise, we design rims to be fit for use, based on their intended purpose. Within the design process of our alloy rims, we use FEA to optimize the rim, looking to replicate an impact and spoke pull through. Alongside this, we ensure to work hard on material choice (6069 T6) or carbon layup to offer this in the best way. We then validate the product through lab testing, as well as ride testing, to see it meets the high standards we set. These tests include, but are not limited to, impact tests and pressure tests, which I undertake here at our UK HQ. We also test competitor rims as it is important for us to work to develop highly performing rims and wheels.
In your experience, what combination best reduces the chance of losing air? Do you see tire inserts as a benefit or hindrance, or does it depend on the circumstances?
A combination of using an ETRTO compliant rim and compliant tyre (both appropriate for the use case of the ride) with good sealant is a great start. Pair this trio with adequate tyre pressure and you won’t go too far wrong. Checking tyre pressures using a pressure gauge before each ride to ensure the pressure is suitable, is important. If you’re not sure what tyre pressure to use, do a Google search of “tyre pressure calculator” and that will give you a good basis to adjust from. An insert may be useful if you want to run lower pressures, but it won’t completely alleviate the issue of losing air, but limit – dependent on which insert is being used. Equally in a race scenario, I can see the benefits, as you will be able to ride it out to the end of the track/repair zone, provided it is a large enough insert!
When designing a tire, rim, insert, or any combination of the three, do you take into account how a consumer might pair these options together?
As previously said, we design with the use of the wheel in mind and to ensure that the product meets ETRTO standard requirements. With ETRTO the geometry of the rim bed and internal side wall/flange/hook are constrained. This should allow the rider to use any tyre they wish.
We test in our lab with Schwalbe as we work closely with them (no inserts used), but that isn’t to say other tyre manufacturers won’t work perfectly in tandem, particularly if they are ETRTO compliant. As you have seen in your previously article we have carried out impact testing with our rims with inserts so do have some good data to work from in our development process. Inserts currently have no standard that we can meet with the design, so at present we have to bear in mind that there will be a wide range of inserts, which will be hard for us to design for them all. We do know however, Rimpact inserts fit nicely, as we have performed rider testing with our sponsored athletes.
How would a rim be best optimized for use with an insert?
This is a fairly large question! (Insert spider man meme pointing at each other between rim and insert companies) It is an area we of course consider. We currently FEA model the tyre or rim without inserts and our test methods in mind, which are based on ISO testing (we choose to significantly elevate the test standards over ISO to represent serious real-world MTB impacts). The addition of a polymer in the rim bead is of course harder to model in FEA.
Cooperation between rim and insert companies could be great to help achieve this and communicating with Rimpact is something Dan, our Technical Product Manager, has already been doing for several years when he has been inputting to our rim designs and running our athlete testing.
Why haven't we seen dedicated rims to deal with the additional forces of an insert?
The rider has the option to run a variety of different inserts which will each provide different pressures in different circumstances. As the use of an insert is optional, whereas a tyre is a necessity to ride a bike, a tyre has a consistent geometry with stresses that are more predictable and tested under ETRTO.
As part of our validation process, rider testing is a big part of this. We know that some of our riders choose to use inserts and that, for us, is valuable to know that our rims can withstand the stresses of an insert, along with any abuse our riders can throw at them.
In an ideal world, what would be the best arrangement?
From our data the current situation is not throwing up serious issues for our customers, however, there will reasonably be a few outliers. It might be interesting if ETRTO was open to wheel, tyre and insert companies alike. Standardisation would be great across the board to allow the different products to work in even better harmony. This will open the market for mountain bikers to further customize their ride and can get them shredding with more options in general.
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I've sworn by inserts for the last 6ish years, they really do what they claim to. I have been experimenting without them a little recently, and while I've definitely had a couple of failures that I could probably have avoided, I do think tire/rim technology has gotten considerably better in the last few years. For example carbon rims with a wide bead seat and Conti's new gravity line of tires is a pretty solid setup. For aluminum rims though, and for peace of mind, an insert is still a no-brainer for me.
In response to your second point, like Cushcore we've conducted extensive testing with multiple impact angles, forces and shapes to identify if it's possible that our inserts could in any way reduce the impact resistance of the rim or tyre. We could not achieve any results reflective of the claims. This is corroborated by two tyre manufacturers independent testing they shared with us. We also have not had a single warranty claim, feedback or image proof of such failures in conjunction with our producs. Please send them to us to allow us to improve everyone's riding experience.
dont do it, i promise you feel like a world class idiot.
As far as broken rims in rim wells - Not sure why you would be talking to tire mfgs about that and not rim mfgs? The rim mfg's would be the ones who would see the failures and not the tire people. Ill gladly send an image along the next time I come across one. To be fair, these failures typically are on lower end rims but the fact remains - most rims were not designed to see heavy loading directly in the rim well and inserts can cause heavy loading in the rim well on an impact that is taken direct and not focused on a single bead hook. Im sure you know, this is why Schwalbe Procore was never successful - it cracked rims in the well.
Your blanket denial that inserts can cause rim damage seems like a big call given the range of rim shapes and constructions available.
BS! Rims fail. Period.
They fail a lot without inserts. They fail a lot less with inserts.
Let's also add up broken rims with inserts vs broken rims with no inserts.
I can tell you that my broken rim count was SIGNIFICANTLY higher before I started using inserts, and again after I experimented without them.
A foam donut isn’t exerting more pressure on a rim bed. Inserts have saved a ton of wheels, makes the ride quality better at that, gives you so much more sidewall support at the limit of cornering grip, it also gives you the ability to run a realistic pressure for grip in technical areas.
But 25psi is going to be acting on all surfaces at the same time.
Is there some background here? Seems like you would agree on a lot.
It's not really the same as applying force to less area via the insert.
No duh
The end of the day wheels are consumables just like the tires that shod them. At least with alloy we can easily recycle them.
I also think people grossly overestimate how much “design” or “engineering” goes into a bicycle rim. As evident by why flats, blown tires, rim failures are still present in top tier racing. Gwin roared to his success without flats because of the FTD, that weirdly launched the whole thing and died an almost immediate death.
Inserts aren't the same as air or they'd be useless. They apply force to different parts of the rim or they'd be useless. So inserts causing rim damage seems plausible.
Goes on to show a firm grasp of how an insert changes the loads on a rim.
If they do cause damage, they certainly prevent a lot more than they cause.
Inserts will help with the sidewall dents but hoop strength comes from a proper wheel build, adequate spoke tension, and a nice stiff rim.
You dented a 511 and didn’t know because the cushcore did its job, it dissipated the energy and acted as cushion on the impact. Without one you would have had a failure from the point load. Your lack of understanding, let alone reading comprehension shows that you’re not fit to make any judgements on what a safe product is.
Tire pressure is omnidirectional, that’s how pressure works.
Show some evidence. So far I see a lot of arrogance, confidence but zero clue.
But what do I know, it's not like I've built wheels for some of the world's best riders and thousands of other wheels for my customers.
I'm asking you for evidence, you just keep repeating your BS. Step it up.
I don't have to be an engineer to tell you that if I've seen a 1000 broken rims, and 0 of them had insert related damage, it's statistically significant enough to say it saves more rims than it damages. Based on the feedback of literally everyone who rides inserts.
And then there's this clown who knows better, has literally nothing to back his statements but is almost as smart as it gets. Try harder or quit it
Try noticing how literally noone agrees with you yet you get all the downvotes. Ever wonder why? Is it because you're so special and know more than everyone, or...? Maybe it's a witch hunt!
I'll bite... tell us who you are.
So far your argument doesn't have a lot of provenance.
It's funny that Rimpact's response to this was "we've talked to the tire manufactures and it does not happen". Why would the tire mfg's be the ones that see the result of this? Go talk ask any larger RIM mfg and they will tell you that they do see it on occasion. This DOES NOT mean that the overall benefit of inserts is negated by this. If used properly (correct PSI) there is still can be benefits to inserts for certain use cases. Two things can be true at the same time, even in arguments on the internet.
I'm sure there's some validity to that argument. It's also worth noting that ProCore ran around 80psi, rather than the 20ish that most people will be running with inserts.
Inserts have also been around long enough now, and it would be naive to assume that rim designers work in a vacuum. A good designer designs product to be used in all kinds of ways that they couldn't imagine. That is to say, they should be designing rims with the idea that people are going to be using inserts, because that's the real world.
Product lifecycles can be pretty long in some cases. Inserts are a more recent thing (~5 years). Once new rims hit the market that have been designed to consider insert impacts, all the other rims already on the market dont magically disappear. Again - two things can be true at the same time. I like and use inserts in some cases. Im not anti-insert. I just find it funny that these brands act like it's totally not a thing when in fact it is and it has a pretty reasonable and rational explanation.
While obviously rim designers shouldn't design their rims to be used as hula hoops, you have to design products knowing that the end user is going to abuse things in ways your testers could never imagine. I spent some time studying and working in Design, and in the bike industry, and we've all seen those instances where people have broken things in absolutely unbelievable ways. That's what people do.
Sure, product cycles can be long, but take WAO for example, they've only been around approx. 5 years, their new Convergence rims certainly haven't been in development that long. I'd be VERY surprised if they designed those rims oblivious to the fact that people are going to run inserts in them. Especially as a local BC brand. I don't think there's anything wrong with pushing the industry to keep up with the way people are riding and using product, that's how we get better products and user experience.
When I'm done being sick..I'll probably not care to remember but I'd be keen to take a rim, old cushcore, the biggest hammer I have and see if I can break the rim bed through that force. Not the best test but it's something!
My entire issue with Mr. Know it all above was the claim that because he flat spotted his rim with an insert, inserts are bad. I just have a difficulty with bs assumptions based on lack of understanding. Well more with throwing feces when people say you're wrong.
But that would be a pretty shitty ride.
The product has to serve the hobby, not the other way around.
Best paragraph was the guy from Roval: if even with the highest end stuff the 200 pound guy still has to "take care to not break something" then there's still work to do.
Inserts allowed running lower pressures which provided a better ride, traction, and handling. But didn't allow running thinner-casing tires. Swapping in a tube on the trail and wearing the insert home like a sash of shame resulted in ditching inserts altogether, and taking the DT Swiss approach. Sidewall support on DD/DH casing tires is good enough without inserts, but it'd be nice to run below 28psi in the rear. Not quite nice enough for the weight penalty on a trailbike.
I think the ratio of air volume to pressure is key here. I have a set of DT m1700 i35 (27.5) wheels that I run WTB Vigilante 2.5/ Trail Boss 2.4' s (both light casings) on and after having ran various tire/ rim combinations on other bikes, this is still my favorite setup. I dont have to push the pressure sky high to get sidewall support and that results in a comfortable, damped but responsive feel. I'm a fat ass at 230 lbs and I get away with just 27-28 psi in the rear.
In my mind, the reason for this is the added volume of the i35 rim and the relatively large volume of the WTB tires.
One of the worst set ups I tried was an 29x i27 rim with Specialized trail casing 2.3 tires. They had to be at least 32 psi or they'd squirm really bad under load. I actually ate shit once due to this tire squirm.
Similarly, I ran Specialized DH casing tires on 29xi30 rims and had to keep the rear around 30 psi or I'd burp the rear under a hard corner. The ride feel and control on both the trail and DH tires was awful at the higher pressure. They bounced around a lot (hardtail) and ultimately left me more fatigued at the end of a long rough ride.
I would like to run inserts at least on the rear the next time I have a tire that wants to be up in the 30 psi range so that I could drop it down to 27-28 and see how that goes.
Yeah with an insert I think I could get to 26/27 or so, maybe have a better trail feel. But so far a DD Maxxgrip without an insert is a better trade on weight.
These statements make no sense to me. I run inserts to allow me to use *lower* air pressure for better traction and also for comfort on the back of my hardtail. Inserts definitely change the handling, but for me they actually improve it.
I wOnDeR iF tHeRe'S a CorRiLaTiOn ThErE.......?
I was never a fan of the theory of inserts until I found myself dinging my rim frequently. I found that 22/25psi was the highest pressures I could run without severely affecting grip and feel. I finally tried tire inserts and they allowed me to run my normal pressures while drastically reducing rim impacts.
Obviously, there were other issues - some good, some bad - but the resistance to pinch flats was astounding.
It is not only grip and reliability, it is a lot more comfort and a very stable tire in fast curves. Well damped too. No puncture since > 6 months when I build it up. Driven two times in a week. On short rides even without a pump because I know that I am able to finish the ride even without air. (Which never happened so far.)
Similarly, the undamped rebound of the tire becomes problematic when the pressure is increased. Some riders would surely want more pinch flat protection, which would have to be achieved via an insert or casing construction to avoid the rebound issues associated with more air pressure in a large tire.
The concern is that a wider rim, very large insert, and/or huge tire with stout construction can create an overly heavy system. How do you feel about these or other drawbacks of your set-up?
I have heard people say Cushcore makes rims weaker. Has anyone's experience born this out? My experience has been the opposite.
Also I will die on the hill that installation is not hard at all with the right technique. The only issue I have had is with the uninstall.
www.bikeradar.com/reviews/components/wheels/wheel-sets/bontrager-line-pro-30-wheelset-review
4 out of 5 failed in the same way. Always in a fast chunky section of trail, usually flat. Never felt like a significant impact, just chunky repeated chatter at speed and then boom, the rim lets go.
Then I switched to Cushcore Pro and I haven't gotten a flat and only damaged a rim once when using the XC on my next bike. Sold. I'd rather stay on my bike and riding all season than driving home with a cooked tire or rim and then waiting a couple weeks for warranty.
I personally use it for the traction and burp protection. As low as I like to run my tire pressures, I'd burp them constantly in flat corners. If I don't run an insert, I have to increase my tire pressure considerably to keep the seal intact. If I'm running a tube, I can run slightly lower pressures (as they can't burp) and after the ride I find loads of grass between tire and rim as apparently I do create a gap when cornering hard. So yeah, the 5bar inside the ProCore tube keeps the gap firmly closed no matter how low of a pressure I run inside the tire.
So yeah, there is no single "moral". Decide for yourself what would work for you and go with that.
The tire would survive any impact but the rim not. Other DH tire casings like Maxxis,Schwable,Continental or Specialized would be flat and your rim broken.
Better try a combination works for you,maybe a crazy combo but if it works for you,nice.
In my local bike park you need any help you can get,DH casing and tire insert is almost mandatory,cos tons of sniper rocks waiting to eat your nice wheels.
Even my Enduro runs on DD front no insert,DH rear tire with Octamusse insert.
"Last season our factory team rider Youn Deniaud raced and won on the aluminum TRA wheels with no inserts"
Conclusion seems to be, buy an affordable alu wheelset and develop skills.
Even my 110# wife has them on her trail bike, front and rear. In her case, she can't trailside repair a tire and she wants to keep rolling for safety reasons in the event of a flat so I just told her to ride home slowly on the inserts.
Yes, that’s it. The future is more policing of useless rules.
Switserland. The centre of the EU.
Also not sure about Belgium (or Switzerland) but across the pond tire pressure is not enforced in any way, you’re free to put yourself and others at risk with your unsafe equipment to your heart’s content!
I happen to use Rimpact inserts, but I think most would give you a better experience. The cost question is a red herring. To get similar performance, I'd have to buy another set of tubular wheels, very expensive tubular tyres, then spend money on someone gluing them up, or spend days doing it myself. Roll a tyre in a hard corner and get grass stuck to the glue? Good luck re-mounting that tyre without a few days of work.
Riding home on a flat with a foam insert isn't my favourite thing, but having ridden home on a bare rim once before, I can tell you what's a better experience with confidence.
ProCore was a cooperation between Schwalbe and Syntace. I've been running the Syntace rim with ProCore since 2018 without issues.
I wonder if it's the type of force that determines the outcome. If you catch a 1 cmsq area of the rim lip on a toothy rock, the inserts mitigate the impact. But if you experience a big compression on large g-out, the insert directs the force into a longer segment of the circumference of the rim well.
I'd be really curious to know if they track their warranty claims failure mechanisms. It seems like something they'd want to keep track of. The two WAO rims I've broken (no inserts) were just replaced with no questions asked though.
Across 4 different MTBs (XC hardtail, downcountry, Enduro and DH) I'm running inserts in all of them because I prefer the way the bikes ride with the inserts. I'm 100 kg and used to have a lot of burping, occasional pinch flatting and on the DH bike, 2 or 3 rear rim denting incidents per season running tubeless with similar tyres to what I'm running now. But with inserts in the wheels I haven't burped a tyre, haven't pinch flatted a tyre and haven't dented a rim.
Tyre grip is up a little, tyre pressures are down a little, confidence is improved and since I've never ridden 3 of those bikes without inserts I can't miss the feeling of a lighter wheel.
The rim is thick and sturdy at the bead hook where impact normally happen. However, to save weight. The carbon is really thin on the rim bed.
Without insert, an impact would happen on the rim hook. Nothing push against rim bed.
With insert, the impact force would distribute on the rim bed, where carbon is thin.
CushCore saying "insert can potentially cause damage is a myth" rule them out from my list of consideration in the future. I appreciate companies that inform people to make informed decision. Ignorance of potential issue is a big no for me.
Another company, that if the above held true, has no vested interest whatsoever, says inserts can cause issues.
Food for thought.
They may transfer some load to the center of the rim, yes, but the rim does not fail at a lower impact force than without the insert. This is what Cushcore claim to have tested.
So for the rider this would imply that if you manage to damage your rim with an insert (for a given pressure, tire/etc), you can assume it would be well and truly destroyed without it.
Then.. as time moved on, and Schwalbe released their PROCORE, I jump on the boat, since it was something well proven on MOTO (Enduro).
With Procore (±400grm), I could use EXO+ tires (±1000grm), runing on the tubless system pressures from 13 psi (yes... thirteen), up to 30 psi on the rear!
Up front, pressures where between 10psi and 25psi.
At lower pressures, the grip (42a & supersoft compounds) it gave to the tires, was mind blowing. I could cross wet and muddy tree roots, at 45°, without major body english.
The inner tube+tire, pumped at 70psi, would grab the sidewalls of the tire, as a shark, and never had a tire burp.
The confidence in the system grew on me, and on all rides, I was leaving any spare tubes or pumps in the car (almost 500grm).
And during this time, the only puncture I had, that wasn't fixed with Stans squirming out of the hole, it was ok, since the inner tube and tire, let me ride back, without any major issue, and having some fun, how the bike handled (cutties were so easy to perform...).
So...
BRING BACK PROCORE!!!!!!
In the end to each their own when it comes to their set up. Your opinion on other riders 'need' for them based on their weight may be one of the most ridiculous opinions I've read on here in quite a while.
Why would I pay the price of a another tyre to fix issue with my wheel and tyre?
Why not bond a stripe of foam to the sidewall where it would be effective. Less mass, easier installation, pay for one part only.
If you are slashing DH casing than maybe.
If desired casing only comes with too draggy compound and thread, that lets shout at tyre manufacturers.
For me... since I started using pressure gauge before every ride snake bites and bend rim flanges stopped.
As such, the compression ratio is very low, such that the exponential curve of the air spring is insignificant and it behaves nearly linearly. It's not like air springs in shocks and forks, which have a compression ratio orders of magnitude higher.
Even so, the spring rate curves can be complicated. If the tire is being compressed by a large object (ex. a flat surface), the contact patch rapidly expands during the compression, which creates an increasing spring rate, rather than a significant increase in air pressure. If the tire is being compressed by a small object (ex. a sharp rock or a small root), the spring curve is nearly flat without an insert.
The insert creates a second spring curve with a higher rate, a different curve shape, and a different - often complex - cross-section. This produces a two-stage spring and a surprisingly complex set of responses from such simple hardware!
Many years ago, a Maxxis tire that was nominally 2.5" wide actually measured 2.1". They're still undersized, but far more honest than before - even when mounted on the same rim width. If someone was concerned only about weight and not the other improvement associated with width, tread design, etc., they could use a modern 2.1" EXO that's about the same width and weight as a legacy tire with a tube.
If you don't need much toughness from your tires, Maxxis' 2.6" models are the hidden gems in their catalogue that offer nearly old-school weight with modern width. 120 TPI and thin base rubber make them lighter than the 2.5" or even the 2.4" equivalents. The 2.6" DHF is well under 1000 g and the 2.6" Rekon can be as low as the mid-700s (older versions were slightly lighter for some reason). I use the 2.6" Rekon on the front of my XC race bike and the balance of traction, comfort, and speed is unmatched for this application.
And would damage even more rims before running inserts.... and the last time experimenting without inserts resulted in a broken rim on the first ride.
Asking for a friend.
Rider weight, terrain, tire choice, all play into these comments and "experiential" anecdotes.
Running lower pressures (sub 25psi) for slab riding has immense benefits along with the added protection of an insert - take a poll from the locals in Sedona or Moab where you need the grip on exposure but the protection from brutal square hits as well.
I’m not sure what makes off road bicycles moving at ~25mph as a typical maximum would need different tire technology than rally cars or enduro motorcycles?!
For example, look at how Schwalbe's casing line-up progressively adds more material near the rim:
www.pinkbike.com/news/schwalbe-announces-5-new-tire-casings-and-2-new-tread-patterns.html
The Market: We don't need no stinking rules!