The New Mountain Bike Revolution: 27.5-Inch Wheels

sc bronson 660So you went and switched to a 29-inch-wheeled mountain bike. Traded in your old ride with its dinky 26-inch wheels and tires. You were sold on the idea that larger mountain bike wheels steamroll over rocks, roots, and ruts and make running lower pressure tubeless tires even better. It’s just too bad the bike business is already moving on the next new thing, 27.5-inch wheels, a.k.a. 650b (the metric name).

Yes, the bike industry is seeking the Goldilocks middle — after going from “small” 26 to big 29, it’s settling on the (maybe) just-right 27.5. Just as in the ski world, where full-bore rocker was then later viewed as an overkill, now with bikes the engineers are saying that big wheels have too-large limitations; some even say privately they wish that the 29er revolution hadn’t happened, that 27.5 came first and supplanted 26, because it combines the best of both sizes.

What it means is that at the bike world’s annual spring industry trade-show in Monterey, California, this week you’ll see a raft of new 27.5 product: SRAM is launching a range of wheel sizes and forks in 27.5 options, Fox will have its 40 FLOAT RC2 downhill fork in a 27.5, and Shimano will introduce new XT and SLX triple chainring cranksets and XT–level wheels. And this doesn’t even count bikemakers — including Scott, Intense, Rocky Mountain, Norco, Jamis, and now Santa Cruz (with the Bronson, above) — embracing the happy middle.

Why is 27.5 is all of the sudden the new industry darling? We asked some of the leaders of the bike industry, Yeti’s Chris Conroy, SRAM’s David Zimberoff, Specialized’s Sam Benedict, Fox’s Mark Jordan, and Shimano’s Eric Doyne, for their opinions and predictions.

29ers are great…for some applications, and some riders
Yeti’s Conroy says that 29ers force a lot of compromises. “You need to lower the bottom bracket a great deal, and standover [crotch clearance] gets problematic.” It’s less of a big deal if you’re taller, of course, but for bike designers there are still headaches, especially with more suspension travel. The way the rear wheel travels also gets difficult, or you end up with a very long bike.

Long bikes are difficult to make corner; bikemakers call them “truckish” and it often takes a taller rider to generate the leverage to lean them over. Also, Conroy says, 29ers can make feedback muted. “A lot of what riders like in 26 is a certain playfulness.” Conroy and others argue that you can get that playfulness back with 27.5, and of course a smaller wheel equals a shorter wheelbase, and part of what bikemakers call playfulness is just about quicker cornering.

Big wheels add weight
A less expensive 29er with its larger wheels and tires (and that much more rim, spoke, and rubber) is going to have fairly heavy wheels, says Fox’s Jordan. It’s expensive to make a bigger wheel even close to as light as a smaller one, and as you reduce materials you have to think about flex, too. And of course there’s that much more material in the bike frame, too. Yes, 29ers still have leverage advantages, but pedaling a heavier bike uphill is never fun. You can attack these issues with dollars chasing lighter frames, but deciding to adopt a 29er full-suspension for under $3,000 means you’re buying a heavier bike. Go 27.5 and the engineering challenges are greatly reduced: Less expensive full-suspension 27.5-inch bikes are a lot easier to make reasonably light.

The new-new of 26/27.5/29ers 
Specialized’s Sam Benedict thinks only some 26-inch bikes will give way to 27.5 and that some will stick around. “We see [27.5] more in the longer travel all-mountain/enduro category than anywhere else.” But Fox’s Jordan says 26 is strictly going to be for the low end — Fox already says the shift has happened because they see bikemakers beta testing 27.5 in all forms of racing, from XC to DH. “If there is an advantage to be had with using a different wheel size then the pros want to know. I think it’s going to blow up.” Yeti’s Conroy agrees, especially for gravity.

As for why the shift is happening now, Conroy characterizes the bike industry as perpetual tinkerers, but also explains that while 29ers took a long time to penetrate the marketplace, once that happened it opened eyes. Bring along 27.5 and suddenly parts makers and frame builders wanted to experiment; they didn’t resist. “You have to look at what’s worked. A lot people laughed at the Prince oversized tennis racket — then it really worked. It’s the same thing with an oversized driver head in golf or rocker in skis. When it works you have to try it.”

And Fox’s Jordan believes that while large-framed 29ers pose some awkwardness, particularly for shorter riders, 27.5, with lower standover, makes most riders comfortable from the first pedal stroke. “You gain the advantages of bigger wheels without having to change your riding style so most people dig it right away.” Jordan predicts that 27.5 may grow to be the most popular wheel size, period. Hardtail 29ers may still sell well, because you get more inherent cushion from the bigger tire contact patch, but he thinks full-suspension 29 will be more of a niche for taller riders.

SRAM’s Zimberoff and Shimano’s Doyne essentially echoed the idea that 27.5 is going to be a big deal. And though neither was willing to make predictions, they didn’t have to: Their companies are rolling out enough 27.5 product to meet demand, which says that the revolution has already happened. Again.

{ 15 comments…read them below or write one }

  • Planned Obsolescence

    I think 26.75 will be the next revolution. At least until we finally realize 28.25 is the real thing. I can’t wait.

    • Dirtbag

      I know right, this phenomena of constantly changing things and bringing out new options to keep people spending is spreading from electronics into other markets rapidly!

  • S.L.

    I can’t wait to go on a ride where someone flats and everyone pulls out the wrong size tube. We’re going to have 6 spare tubes, they’ll all be the wrong size, and someone’s going to fill their tire with leaves and ride the rim home. It’s gonna happen…

    • michael frank Post author

      @S.L. I’m laughing pretty hard reading your comment… But, since I’ve stretched 26-inch tubes to fit a 29 (a lot of folks do this as their go-to, in fact) the key will be to only bring 26 as your spare tube, and it’ll stretch fine for everyone in the posse. What you can’t do: shrink a 29 to work in a 26, etc.

      • Ryan Johnson

        @michael frank Just to be contrary, I can tell you that it’s just as easy to fold a 29″ tube within a 26″ wheel/tire combo to create a perfectly rideable wheel to get back to the trailhead. I did this a month ago after suffering a flat that would not seal up with latex sealant in my UST tire. I laid in the 29″ tube and folded it, opposite the valve stem. While I half expected a lumpy ride, there was no such effect. In fact, I’d forgotten to remove and replace the oversize tube (riding the bike numerous times on the trail and some paved riding) until I decided to patch the tire and reseal with liquid on the eve of a recent marathon event. At the end of the day, I agree… any tube will be better than none, no matter what wheel size you’ve got on your bike. And speaking from experience, air in a tube is better than a tire stuffed full of leaves and pine boughs.

      • gmats

        Haha! That’s almost true. But I was out riding with my friend, I had a rental 29er, he had a 26. He pinched and then blew his spare tube up. So I put my 29er tube in to his bike. It’s still there, rolling along.

  • Kevin Riedel

    Just gotta ride what works for you and your style. I demoed a long travel 29er at a manufacturer demo day and was sold. It fit ME perfectly…. not saying it will work for everyone. Hope I have the opportunity to demo a 27.5 this year. It might make me change again. Or it might make me confirm that an LT 29 is best.

  • JT

    I guess I’m fortunate to be sorta tall. In my 4th season on my 29er Gary Fischer Hi Fi+ and love it in the knarly stuff. Still have my ’95 Cannondale Killer V 900 (26″ hardtail with 60mm headshock) and ride it from time to time for kicks. It beats the crap outta my old body, but sure ’nuff, it is fast, nimble and light. OK for a short ride or on ‘groomers’ but when the rocks and roots abound, give me the 29er.

      • Bkidd

        I just recently rebuilt my old Delta V 900, the predecessor to the yours. it was cool dressing it up with new sram X.0 components. i lucked out the LBS had a totally rebuilt 70mm head shok that the owner never picked up so I got it for their labor cost. I think when I was done it weighed in at 26.5lbs. raced in a couple of TT’s. It was a fun project, I just scoured Ebay for 1-2 yr old stock.

  • Randall

    After riding a 26 inch mountain bike since 1986, (yes, my Gary Fisher had bull moose handle bars and yes, I am old). I bought a full sus 29er this year and BLAM was I happy! I can honestly say that despite some getting used to, particularly going fast downhill on single track, I will never ever go back to a smaller wheel. The difference is dramatic. I don’t feel the same dramatic difference after riding my buddy’s 650b. 29 inch wheels give you wings… it’s not the Red Bull.

  • Andre Shoumatoff

    I was an early convert to 650b back in 2008 when the first 650b tire came out (the Pacenti Neomoto — this tire rips). I bought it because I’m tall with long legs and I was trying to find a tall frame which a short top tube that I would fit on, and I didn’t mind having to order my tires online only instead of the local bike shop, which I do anyway. I’m not a zealot either, I actually dumped my 650b bike last year in favor of going to 29er. I have lots of time on all three tires.

    Anyway, 650b rips. There is actually something to it. It completely lives up to its name, and it rolls closer to its 29er cousin but pedal closer to 26″. There really is something to it. I’m happy to be on my 29er but my 5″ travel trailbike 650b was the best handling bike I can fit on. I understand these where these short-sighted comments about small difference between tire sizes come from, but I will say with time on all three there is something to it. A lot of it is preference. This video really adresses it well. the guy who says “I wish it hadn’t happened, you can build a good bike out of all three.” http://www.bikemag.com/gear/exclusive-video-bronson-santa-cruzs-new-650b-trail-bike/

    My 29er right now (a Turner Sultan) is one of the best handling and powerful and hungry and most efficient trail bikes I’ve ever ridden. But when you step up to bike makers who mostly only make good bikes (Santa Cruz, Specialized, some of the boutique manufacturers), there is a difference. It is about personal preference so it can be hard to go wrong. But I’ll tell you I personally won’t ever ride a 26er again, unless I’m looking for a super long travel bike like a 6-7-8″ that is more down hill oriented. This is the only way I’d consider it…

  • Vallie Atkinson

    I just converted my Firebird to 650B with Sun Ringle Expert wheels and 2.3 Neo Moto tires.

    I am totally sold!! And 6 months ago I told my friend 650B was dead, and would fizzle away.

    I have switched back and forth between 26 and 29, and when on one I missed things about the other. Recently I did 4 test rides on the same rocky, hilly loop. Endorphin, RIP-9, Firebird, and Firebird 650B. After the Firebird loop my legs felt the best, and I decided I did not care that a few places I liked the feel of the RIP-9, I was keeping the Firebird.

    Then I rode the Firebird 650B. Not only were my legs fresh at the end, but I loved the feel of the bike, and at no time in the ride was I wishing I was on my 26er in this spot, or my 29er in that spot. For me, it finally makes me not want to have both sizes in my stable, and not miss the “other size” every time I ride one or the other. Finally I found the size that suits me everywhere.

  • ricky

    Kevin Riedell’s got the right idea.

    There’s so many riders whinging over the wheel thing and aiming their frustration at bike companies. I know the exact type whining though. They used to play golf before riding became the dork fest it now is. It’s not a big deal. The way I see it, it’s more options to consumer anyway, no?

    Not if you’re a pleb though. ‘I sold my 26er, 29er’s are the future’. You know the guy… Mr Latest and Greatest. Bike companies havent re-invented the wheel, they’ve met the demands of patient consumers (like me) who looked at and tried 29ers and said ‘It works but I dont want to ride an ox wagon’ so we didn’t sell up immediately. However, unlike me, Mr Latest and Greatest just felt the speed benefits instead of feeling what he actually needed from a bike and now doubts his purchase.

    As expected though, 27.5 found found their traction and only now are we getting some really cool options. Personally I feel that 28 would be the absolute winner. But gut feel says thats a wait too long.

    I’ll probably take another 3 months now deciding what to buy, then another 1 trying to find it on a deal or something. Mr Latest and Greatest already has his 29er on ebay and is arguing with his bike shop for selling him the wrong bike by 1.5 inches.

    I wish golf would have a little breakthrough and entice these morons back.

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