It seems that Intend want to be thought of as the crème de la crème of mountain bike suspension. When they saw that their rivals from across the Atlantic - Push Industries - had unveiled an
upside-down fork at Sea Otter last spring, it got them worried. Based on the images, Intend thought Push were working on a fork with sliding bushing technology - something that is common in high-end motocross suspension but so far not often seen in commercial MTB forks. "If that is the case," they thought,"it would be our responsibility at Intend to upgrade technically."
They then began to develop an upside-down enduro fork with this design. This idea promises to cut friction in high-load situations by maximising the distance between the bushings as the fork compresses.
Intend MOTO Details• Matching fork & shock kit
• Fork uses moto-style sliding bushings, carbon stanchion guards & dual-compound seals
• Fork travel: 180mm, 170mm, 160mm, ...
• Shock: 55-75 mm stroke, Metric & Trunion
• Adjustment: Low-speed compression &rebound (fork and shock), custom valving
• Air spring with tunable progression (fork and shock)
• Claimed fork weight: 2,475 g
• Claimed shock weight: 450-550 g
• Price: 3999€, inc. 19% VAT
•
intend-bc.com Intend has finally released the fruit of this one-upmanship. The fork is based on the Intend Flash fork and integrates the sliding bushing tech and a few other features. The moto look is completed with carbon stanchion guards and a colour scheme inspired by motocross suspension from KYB and SHOWA. It's sold as a suspension set alongside Intend's Hover Gamechanger rear shock with a matching colourway. Only ten such sets will be sold, each costing a cool €3999, although Intend did add "let's see what the future brings."
Intend see this offering as "An engineer's dream come true. Unrestricted by costs, efforts, ease of assembly and serviceability."
Oh, and Push never did produce a fork with sliding bushings - not yet, anyway - so this is one of very few MTB forks you can buy with the technology.
Why sliding bushings?
In most MTB forks (whether upside down or conventional), there are two bushings that are fixed inside the outer legs. Their job is to allow the inner tubes (stanchions) to slide through with minimal friction yet minimal play. The distance between the two bushings in each leg is called the bushing overlap. When the fork experiences lateral forces due to braking or landing to flat, the bushings become side-loaded, and this increases friction between the stanchions and the bushings. Just try pushing directly downwards on the grips of a bike without applying the brake (so the force is not parallel to the stanchions) and you'll feel how much friction this side-loading can add. The more overlap, the less the fork will be affected by side-loading and so the lower the friction in dynamic situations.
But traditionally, there's a limit to how much bushing overlap a fork can have, because both bushings must be far enough away from the closed end of the outer leg that the stanchion tube can slide out the other side to the distance of full travel and still leave room for oil and air inside the outer leg at bottom-out.
With sliding or dynamic bushings, one bushing is connected to the outer tube just behind the seal head (as per usual), while the other is fixed to the end of the stanchion tube and moves with it. So, as the fork compresses, the distance between the two bushings increases and is generally greater than can be achieved with fixed bushings.
Why don't all forks have sliding bushings?Intend offers three reasons: "manufacturability, ease of maintenance and cost". It's easy to see how maintenance is harder - having a bushing on the end of the stanchion means the seal head must be removed before the stanchions can be slid out (as shown in the video above). As for manufacturability and cost, Intend spell that out too: "Normal bushings in bicycle suspension forks are made from a soft aluminum alloy with a reasonably flexible PTFE sliding layer that can be adjusted to the tolerances of the housing and tube through simple compression (also called calibrating), motocross sliding bushings are made of a bronze backing and a rigid PTFE layer. These cannot be calibrated and must fit precisely. If they don't fit, it either jams or has too much play. Those issues are not as critical for a 200kg motocross machine as they are for a 15 kg mountain bike."
Then there's the fact that you have to make two sliding surfaces instead of one - the inside of the outer tube as well as the outside of the inner tube. It may also be a clue that the claimed weight of this fork is 125 g more than the regular Flash enduro fork on which it's based.
Construction and detailsThe fork is a collaborative effort with dual-compound wiper seals from SKF, carbon stanchion guards from Rulezman suspension, sliding bushings from S-Tech and custom-manufactured upper tubes from Intend's Austrian turning shop.
The fork is available with 180, 170 or 160 mm travel, and the shock is available in most sizes: 250 Metric / 225 Trunnion by 75mm stroke, 230 Metric /205 Trunnion by 65mm stroke, 210 Metric / 185 Trunnion –by 55mm stroke (all strokes can be reduced by 2.5, 5 or 7.5 mm).
The shock is fitted with a shim stack to suit the intended bike, but apart from the hard-anodised external parts that change the look of the shock, it's no different functionally to the standard Intend Hover shock. The fork can be re-valved for especially light or heavy riders too.
Both units are supplied in a moto-style hard case with a shock pump for 3999€, inc. VAT. For comparison, the regular Flash fork and Hover Gamechanger shock go for 1949€ + 1079€ = 3028 €.
intend-bc.com
Also saying that your partially refreshing your damper oil, is like spraying febreze on dirty clothes and saying you washed them.
I'm not by any means saying that MTB stuff is hard to work on, because it's really not. but I know with absolute certainty, that you aren't touching the bushings at all.
-Take off the front wheel,
-Drop the fork legs from the triple clamps,
-Loosen the damper but don't remove to keep the oil in the tubes,
-Remove the footnut, and rebound rod
-Drain the bath oil
-Remove the damper, spring perch, and spring
-Pop the dust wiper off
-Remove the seal head retainer clip
-Pull apart the inner and outer tubes
(This will pull out the bushings and Seals together.
-Damper rebuild is nearly identical to a fox 40.
Obviously replace all bushings and seal at this point, change the damper oil and headset and Midvalve Seals.
Reassemble in reverse order, and fill bath oil to desired level based off rider preference.
Overall, not much different from MTB stuff, but just easier when it comes to buahing service.
The only drawback is MX suspension is heavy, so it's a bit more cumbersome.
That said, the moto industry does a far better job of valve design and shim spec than MTB, and it's due refinement and QC, not crazy expensive tech - Craig at Avalanche has been using those same designs for 20+ years. MTB industry just seems to love (over)complicated damper designs executed without much field testing and poor MFG quality control. MTBers don't help themselves by shopping for cool-sounding novel features vs. well-executed standards. And despite not being particularly weight-engineered, moto forks are not cheap. Retail on OEM forks is typically $800-900/leg without triples or steering stem, and A-Kit with more sophisticated damping runs $5k-$8k.
I get that it’s probably not required in a moto fork with vastly larger oil volumes, much more tolerance for friction and far fewer weight constraints. But a fork where you have to press in new wipers and bushings every time you pull it apart would be a total non-starter in the Mtb world.
Your service intervals on moto suspension is approx every 20 hours (for track rising anyway) vs approx 100 hours on most MTB suspension. The forces applied to moto suspension are significantly higher and the lifespan of the serviceable items therefore don't experience the same life expectancy.
Overall, generally with moto suspension, when you pull it apart, replace all the serviceable items. This equates to once or twice a season, depending on how many hours you run. In all reality, the motor service intervals are substantially lower. I do my engine oil every 2-3 hours, and I'm lucky to get about 6 hours out of a rear tire and not much more than 12 out of the front.
Chain and sprockets once a year.
The engine will get a top end rebuild around the 75 hour mark (new rod, piston and timing chain), and clutch pack will likely get replaced around the 30 hour mark.
Overall, most MTBs are extremely reliable, and very low maintenance compared to a true MX race bike.
Add in a HC piston, and now you gotta run race gas at approx 15-20$ a litre.
My moto, I have been riding more often, and didn't race this past season as I've had other commitments, but I generally keep my service intervals the same as I would if I was.
TL;DR: Good to see the floating bushing concept making the fork stiffer the deeper you dive into the travel. But is that the critical scenario which makes it worth the (supposed) complexity?
That is when you have massive lateral (fore-aft) loading, AND are deeper in the travel so the sliding bushing will be significantly spaced from the fixed. If your fork feels harsh under braking, this could be at least one of the culprits.
Outside of braking, not a huge deal especially on shorter travel forks. But braking through the rough stuff is one of those moments when good suspension is a beautiful beautiful thing.
It may help to visualize if I highlight the other major advantage is a significantly stiffer system in the scenario above - much less total deflection, means less strain at the loading points, means less delta/angle aka edge loading. Not to mention, that fore-aft stiffness makes a dramatic difference in handling and control by maintaining trail and tracking, aside from issues of compliance.
Ermmm. Thats not the correct reason. Can we please get some proper tech editors at PB? It's embarrassingly bad at the moment.
I've always wondered if you two were the same person, or you both are just really into tin. Now seems as good a time as any to ask, lol.
@Brigh Racing Shocks has been making screw bushings for over ten years
Peli cases are EXPENSIVE!
Can't really justify getting a Peli at this point, but someday...
Mi sembra che intend abbia dato una scopiazzata ...
www.vitalmtb.com/news/press-release/bright-racing-shocks-releases-new-skunk-fork
It'll be years before they can consider that suspension could be in a fork.
If only Cannondale would make a 220mm lefty DH
@Breeconay: Giant also spec the Fox 32 fork on their Revolt X... doesn't mean they sell them in decent numbers. Certainly not in the UK at least
I’d also like to ask why you’re calling a mountain bike ‘moto’ which directly means ‘motor’ but obviously is a derivative of motocross. Inverted suspension forks are not unique to motorcross and evokes memories of early 2000s with 20mm axle standards which were actually a carry-over from motorbikes and I’m not sure you want people thinking about old technology with the launch of a new product.
Bright is by far the best performing fork around.
Who's poorly informed NAO?
He wrote a review on the Bright Racking Shocks fork in 2021, so I think he knows about it.
a usd AND floating bushings fork is not easy to develop in the right way
it' not just enlarge the upper tube inside diameter and redesign the upper part of the leg, adding a bushing.
if you want to develop a fork in that way, there's too much thing to rethink
this look to me like just a quick project. and those upper looks too thin and flexy.
I prefer the previous Intend project. but over all I prefer the mind behind Bright Racing Shox. with years of develop (remember Fimoco and Race Factory right??) in the floating bushings system till the first era of mtb
No. sorry but this time Intend disappointed me
From 01:00
youtu.be/uvLdCPausWo?si=tjkqKJB9DqW6Y86l
From 03:16
youtu.be/6dC8CVKaUe0?si=tUpKganE50hJTIlr
www.whitehouse.gov/briefing-room/statements-releases/2021/10/18/fact-sheet-biden-harris-administration-launches-plan-to-combat-pfas-pollution
Amen brother!
I used to come here for tech advice- ameeting of minds. Thought this might be an opportunity to open up the torsional rigidity debate again.
Now it’s a meeting of puns, dentist jokes and downvotes..
The technology with "sliding bushings" is anything but new. There is already an Italian manufacturer who has been installing this for years.
Look at www.brightracingshocks.com
www.planooutdoors.com/hunting-storage/rifle-shotgun-cases