For the dozens of you lamenting the static nature of the wheel size debate over the past few years, this one's for you. WTB has announced their development of a new wheel and tire size, primarily focused at the gravel market. The new
750d distinction is currently aimed exclusively at the custom-built-to-order market, as the diameter is large enough to require specific frame geometry.
750d is not meant to replace the tried and true 700c, but merely complement it and cater towards taller riders and those who want a more efficient ride over washboarded and rougher gravel roads. The larger wheel size is also meant to offer a larger contact patch than traditional sizing, closer in comparison to 29x2.4" mountain bike tires. Why they're not just using some of the many already available fast-rolling mountain bike tires, I don't know, but hey maybe I just don't understand innovation.
The rim designation for 750d is 660, which is 38mm larger than 622 (700c/29"), which is 38mm larger than 584 (650b/27.5").
There isn't currently any production timeline for the 750d rims and tires, so availability will be limited for the time being. WTB says aftermarket availability is contingent on OEM adoption, so if and when the drop bar world moves to adopt the new standard we may see more of these larger hoops rolling around on the gravel roads we use to get to the actually fun part of cycling.
I like gravel bikes because they're efficient enough for the weeknight roadie group rides, perfect for weekend cyclocross in the fall, and ok enough to get you down some singletrack on those big weekend adventure rides. They've done a good job at turning 3 bike segments into one, a boon to wives and girlfriends everywhere.
Let people be weird and enjoy what they enjoy.
Gravel bike also seems to be a good platform for a bike-packing setup for family trips. With a 5yo, a 7yo, and a wife who is a beginner level mountain biker, we're not likely to be doing trips on the kind of terrain that would require a mountain bike. We've done some short trips and would like to do more of that kind of travel. For those reasons a gravel bike is next on my n+1 list.
Gravel bikers are the crossfitters of the cycling world. The comments and lack of sense of humor confirms this.
Regarding the 750 rims - if you guys have ever seen a size XL or size 60/61/62cm gravel bike the 700 wheels look tiny on there. Much like an XL 27.5 MTB can look.
Bahahahahaha
Sigh
If the ride was 30% road and 70% off road (including some small drops and jumps etc) suddenly an XC bike would be way better.
@TET1: The "World Champs" scene in SoCal is huge. I don't know about other place, but I know of a "Worlds" every Tuesday night, and two crit races in pedal range on Thursday night. A dude I know does one on in a rich neighborhood every Wednesday at lunch, and another guy I know does one Wednesday mornings. These are all treated as races, not fast group rides. And you will likely find some pretty fast people, as in actual national pros attending. I haven't gone in a long time since I haven't been interested in socializing (I'm very introverted).
Would be fun to see that in group ride format.
www.youtube.com/watch?v=CB9lf9BqgmQ
Gravel bike filter please, PB!
- It's still an experiment and may evolve into something different.
- The reason they aren't just using a larger MTB/Gravel tire pertains to aerodynamics, ride quality, and contact area: Moots says that a 40c 750D tire effectively has the contact area of a larger 48-52mm 650B tire, but in a longer and narrower contact patch. They say this is more aerodynamic for the same level of float, and the ride quality at higher speeds is better/more controllable than 650B in their experiments so far.
- Part of their initial prompt to explore wheel sizing was with difficulties optimizing the range of 1x drivetrains for gravel riding around a desired speed range and tire size, and the larger wheel size helps them optimize a gear range for the desired speed range with a desired tire size, while also claiming the benefits above.
- They see this tire optimized for a certain speed range. They said that generally for gravel, they see 650B as a 14-18 mph tire, 700C as a 15-25 mph tire, and 750D as a 17-30 mph tire.
- Because of the speed range, It's ultimately optimized for racing or higher speed riding.
Though I see it as a useful standard for those long travel expedition setups. The issue is you won't find replacement tires if you have issues.
Did they develop a new wheel size rather than changing a chainring on their existing bike?
I thought these days we all believed that fat tires at lower pressures were actually faster on rough terrain. Is it really faster than the 29er setup in anything but really high speeds due to aero differences?
Perhaps longer contact patches engage more gravel tired-sized block knobs, and therefore grip better and let the rider corner faster.
Sure would be easier if we'd all use ISO tire size names. I watched a coworker struggle with a 26 x 1 3/8" tire just the other day. He needed ISO 590 and was trying to fit a 597 (almost exploding the tube in the process). I'd blame it all on the US's failure to convert to the metric system, but you've still got Continental and Schwalbe in Germany calling their tires 28-inch.
The immediate and violent backlash against this new wheel standard gives me some hope, TBH.
Contact patch science assumes that the tire is a slick but that theory doesn't work for treaded tires.
Unfortunately, as we all know, this is what will happen whenever standards are "nuked"
xkcd.com/927
You'll find me at the trail head this weekend saying something like: "No, blacks for me today. I'd die on this 29er I'd need at least 750c wheels to ride that"
And tbf, the Cutthroat is basically a hardtail with (very wide and flared) drop bars. It's marketed towards folks who are swapping their MTB wheels onto it for 2-week long bikepacking adventures.
650B actually meant 650 outer diameter and a 32mm tire height, which got pretty close to the ETRTO Bead Seat Diameter of 589, but using the B for MTB tires was just stupid, because they're all closer to 60mm in height/width.
700C was the same idea with 700mm outer diameter and a 39mm tire height, which again is pretty close to the 622mm BSD of road wheel and 29ers, but the actual C height/width is only just now being used on road bikes.
750D should mean an outer _tire_ diameter of 750mm and close to 45mm of tire _height_, which does get close to the BSD of 660, and will probably represent a fairly common actual tire height/width, but it still adds the complication of 750 not always being the actual tire diameter and D not always being the actual tire width.
AND, we don't call 29ers "700C", because that would be stupid, and it's why 650B nomenclature faded away. Despite 27.5 being also stupid because, given the same tire height/width, it's exactly 1 inch bigger in diameter than 26, not 1.5 inches bigger; though it is 1.5 inches smaller than 29, which maybe should have been called 28.5...
It should have been named by it's BSD. 660 has a nice ring to it, and with more manufacturers displaying the ETRTO metrics more prominently, it becomes obvious which wheels are bigger. "40 x 750" is just dumb, and actually wrong if that tire is really 40mm high: outer diameter will be 740 in that case, not 750.
559
584
622
660
Sorry if this is a nerdistic view... But I find elegance in simplicity
Quite many times I've had people ask my the difference between ' 28" city tyre ' and ' 29" mtb tyre ' for example
Ie., if you're as tall as Shaq, make as much money as Shaq, and want bespoke everything like Shaq, then this is for you. All us normal plebs need not apply.
Most bikes in the 'progressive' side of the gravel spectrum are growing in terms of reach, bringing stems shorter and meaning no toe overlap (I challenge to get toe overlap on the new Stig, however big your feet are). That said, where do we draw the line between mountain bikes and gravel? Oh yeah, with stupid new wheel sizes. No thanks.
I mean yeah, the TCX is a cross bike, of course you're getting toe overlap
bikerumor.com/wp-content/uploads/2023/08/Moots-CRDD-prorotype-750D-new-wheel-size-MADE-show-WTB8-scaled.jpeg
Of course it can happen in a handful situations in which you are going very slow or are track standing. But I think it’s relevance is blown way out of proportion. It’s like complaining about the reduced steering angle of a double crown fork. Yes, that too can become an issue, but it very very rarely does.
It's not larger, just longer and skinnier. Pressure is pressure, it doesn't care how big the circle is. The same PSI will give the same square inches of contact per pounds. So unless you're lowering pressure or gaining weight when changing wheel sizes, the contact patch won't be larger.
700c on 63cm and larger looks like an out of proportion clown car.
Correct the trail and move to proper chain stay length for the biggies.
Perfect OE application is the KHS Flite 747 (a Leonard Zinn derived bike).
That has 200mm cranks and the larger hoops really would be mathematically correct.
If there is a market it will catch fire - then get reflected in the larger OE world.
We’re talking custom frames for people used to buying special due to their circumstances.
I’ve got a GT Tachyon w/ the D size wheels.
That one sorta flopped.
It would be cool to see someone build a test frame with interchangeable dropouts to go between all three wheel sizes (assuming WTB offers the same tires in all sizes) and compare efficiency & comfort on various surfaces. I'd imagine these spin up super slow, but if they're a bit more efficient, it might be worth the trade-off.
In order to keep these from feeling sluggish, they'll need to keep the rim/tire weight down. However, if they try to use standard dropout spacing, I bet they'll end up with a lot of lateral flex, be hard to keep true, and break spokes faster than the typical 700c.
Side note. So Levy is gone? Seems like a really long vaca…
Just saying maybe lets wait & see what sticks, maybe it's dope.
Hell, I'd build some mountain bikes with 31-32" wheels if they did a decent tire.
Good on ya, WTB.
We were so close to having really nice standards across most lines; boost on a mtb, 12mm axles, we needed something to shake things up I guess.
Custom frame builders must also be pumped.
I'll keep riding my 2018 diverge for now though
A few years back I was riding 32" on a mountain uni, I broke down a Walmart cruiser bike to scavenge the rims/tires, it made a great XC wheel size, glad it finally caught on.
That said, this is a new standard we don't need.
Also WTB: "but it's the SAME OD as a 29er MTB wheel and tire, so it's really the same"
Excuse me while I jump off a bridge.
WTAF is this.
26” for life!
And if you're old enough to recognize that quote, you should also know that the vast majority of 90s mountain bikes didn't have thru axles or any way to mount disk brakes. Sure you can slap some curly bars, skinny tires, or even a clutch derailleur on one, but I don't know why anyone would, especially if the goal is actually riding gravel and/or roads.
Then ride on the road, or get a mountain bike.