Saturday, September 15, 2007

The 650B Experiment

For the past couple of months, I have been exchanging e-mails with Kirk Pacenti about 650B wheels. Kirk, who makes some of the nicest lugs on the planet that are used by some of the world's best frame makers, has been a driving force behind the 650B movement and has been a great source of information.

Based on Haro's success in the 29" wheel market with our line of "Mary" steel hardtails and the fact that 29ers just ride so damn nice, I was naturally intrigued by the whole concept behind 650B wheels. With 650B wheels measuring 27.5" in diameter, they are halfway between a 26" wheel and a 29" wheel.

From a manufacturer's standpoint, the real advantage behind this "tweener" size is you can run a 650B wheel on a 26" wheel bike with very few modifications to the frame itself. 29" wheel frames require a whole new drawing with revised geometry to accomodate the larger wheel size. And then there's the tooling costs associated with a new frame design.

From a rider's standpoint, I was really curious to see how a set of 650B wheels would ride. I'll admit that I was hugely skepical of 29" wheels (like many people were/still are) until I rode one. After you throw a leg over a 29er, it doesn't take long to realize the obvious benefits that 29" wheels have to offer. However, 29ers do have their pitfalls (not many, but they do exist). They are a little a little harder to get started from a standstill and they don't really excell in really tight technical sections and switchbacks. Would 650B be the solution?

I ordered a couple sets of Neo-Moto tires from Kirk and 2 sets of the new "Blunt" wheels from Velocity. Based on the rim and tire dimensions we got from Kirk, it looked like this tire and wheel combo would work on our 6" travel Werx Xeon all-mountain bikes without any modifications, so we could start testing right away once we received the wheels and tires. It would be close, but at least we would have to wait for sample frames to be made.

Pacenti Neo-Motos on Velocity "Blunt" wheels.

Last week, it all came together. We got 650B wheels and tires. Product Manager Pat Crosby mounted them up to a Werx Xeon and they fit. Tightly, but we have clearance, Clarence. The Fox Talas fork had about 1/4" to spare between the tire and arch. The swingarm yoke is also tight...about a 1/4" there too. The front derailleur clearance is real tight. Better hope I don't pick up a stone in the tire or the FD will be toast.


Even tighter.

Today I decided to do a little test. I took two Werx Xeons out to a local trail that has a little bit of everything on it: climbing, semi-technical descents, switchbacks, flats, etc. One bike had the 650B wheels on it and the other had stock 26" wheels on it. I have to note that although these were both the same model bike, they weren't spec'd identical. One had a Fox Talas while the other had a Fox 32 Float. One was SRAM X.O, the other was new Shimano XT. Both had RockShox Pearl 3.3 rear shocks, which I set up as close to identical as I could.

I took the 650B bike out first. The first part of the trail is an off-camber rolling singletrack section with a few little rocky sections here and there to negotiate. So far, so good. The bike really felt smooth and hopped over the rocky stuff easily. Not much elevation change of any great consequences, but wheels rolled confidently on the small descents and climbs.

As I pedalled along a wide-open flat section, I was amazed at how fast I was going with what seemed like very little effort. Much like a 29er, even though bigger wheels might be a little bit harder to get rolling, once you do get them going, it doesn't require much effort to keep them going at a good clip.

I negotiated a few flat but soft sweeping corners in both directions. The bike felt ultra-stable and the Neo-Moto's hooked up really well. I didn't feel nearly as squirrely as I sometimes do on a 26" wheel bike in these corners.

The true test was going to be the switchback section up ahead. They aren't terribly steep, but they are a bit tight and they tend to be loose from everyone skidding through them on the way back down. On a 26" wheel bike, I rarely have a problem through them, but on my 29er, it's 50/50. Sometimes I clear them without dabbing and other times I'm not so lucky. Today on the 650B bike, I sailed right through them. I'm impressed.

Just up the trail a bit is another uphill switchback I've never been able to clear on a 29er and sometimes I even dab it on a 26" wheel bike. It's a real tight one...almost tighter than 90 degrees with a little wood water bar step right in the apex. Again, sailed right through it on the 650B bike.

After this weird little switchback, there's a fairly steep climb with some loose sections and rocks in it. The tires are hooking up like there's no tomorrow, even in the loose stuff. Am I on a 29er? Hopping up an over the rocks was a breeze. At this point, I hit a few rock gardens on the way back down the hill...again, I'm asking myself whether or not I'm on a 29" wheel. The 650B's are rolling through stuff like it doesn't even exist.

I rolled back down the same switchbacks I just got done riding up, and the bike did equally well on the descent. The most impressive thing was the feeling of control through these switchbacks. Since I went into them with much better stability, I didn't find myself getting squirrely through them and skidding around as much in the loose stuff. It sort of felt good to know I was minimizing the impact on the trail!

Time to give the 26" wheel bike some love. After swapping bikes out at my car, I rolled down the hill to take the same exact loop I just finished on the 650B bike. As I suspected, the 26" felt twitchy and small. On one of the little rock sections in the off-camber singletrack, I actually dabbed...just didn't have the momentum to get through it. The beauty of 650B and 29er wheels is you need FAR less momentum to get through the choppy stuff!

As I cruised along, I made notes of some of the differences I felt. Cornering wasn't nearly as stable. Climbing didn't feel as efficient. The switchbacks were just as simple to negotiate on the 26" wheel bike as they were on the 650B. The technical downhills definitely weren't as smooth.

Overall, my first impressions of 650B wheels are pretty good. Very similar to a 29er, it just gave the bike a nice, stable feeling. The best thing about it was I was on a bike made for a 26" wheel, so I didn't feel like I was riding a stretch limo. I'm eager to get more rides in with the wheels; the first day was awesome. Do I think the 650B wheels will replace 26" wheels? No, but they did make me love riding one of my favorite bikes even more.

It's also good to know that from a manufacturer's standpoint, there's very little we'll need to do with our 26" wheel frames to make 650B's work. All we have to do is lengthen the stays a bit. I don't have a high comfort level with the amount of fork arch clearance we have, so the choices will be to either spec a 29er fork or hope that fork manufacturers will see 650B's as an area of opportunity and provide for more clearance in their castings. As mould charges are quite high for those castings, I don't know that we'll see that happening in the very near future or not.

One last impression I'll leave you with is the overall look of bikes with 650B wheels. They just look so balanced! 29er's often look they are all wheels. I know that's sort of a "chick" observation, but I'd like to think overall aesthetics do play a roll in the function to a certain degree.

Nice and balanced!

So are you curious yet? If you'll be attending Interbike's On Dirt Demo, we'll have 2 Werx Xeon bikes out there set up with 650B wheels. Come on by and take one for a spin. I'd love to hear as many opinions as possible on this to help us decide if it's something Haro should put into our line.

Happy trails!


MMcG said...

Why lengthen the stays if you don't have to - perhaps some seat tube modifications would do the trick - or finding some derailleurs that will work better with the 650bs?

Just some food for thought, since one of the positives touted for this tire size was that you could design a FS bike without mega long chainstays.

Thanks for the post and photos. Those Blunts are sexy rims!

jill hamilton said...

The stays won't need to be lengthened a lot...but they will need to be lengthened a little since I'm not comfortable with the current amount of clearance in the swingarm yoke. There's less than 1/4", so that doesn't give much clearance for mud for our friends in areas where they actually get rain!

Guitar Ted said...

I'll be there and would love to give you my take on that rig with 650B wheels after a ride. I'm genuinely intrigued by the format. Your commentary is telling and may change my take on where this stuff will be going in the future.

Kudos to you and the rest of the Haro crew for your pro-active approach to your bike line and new innovations. ( if you can call an almost 60 year old wheel size "new"!)

Look forward to checking these out in a week or so!

MMcG said...

Also - would there be any chance of tire rub at full travel with these larger wheels on this "demo" set up?

How much longer will you have to make the chainstays? More than an inch do you think?

Is this the least expensive way to re-design and hence the reason it needs to be a chainstay modification rather than a change in spec'd derailleur (etype?), and or a change in the seat tube configuration?

jill hamilton said...

While I'm not an engineer, it really doesn't look like we'll need to lengthen the stays much at all. No where near an inch...I'm thinking a 1/4" to 1/2" max just to get the tire more centered in the yoke where it's supposed to be. By doing this, it will likely cure the FD clearance issue as well.

Product Manager Pat does all the bike drawings...he'll start working on that aspect of it to determine what the "magic" number will be.

No tire rub issues on the seat/seatpost in my test. Didn't even come close. My guess is the rear shock would have to damn near be out of air to have that happen.

gm1230126 said...

If you like the ride and setup of the 650B where you have it now perhaps you could curve the seat tube to give you the additional tire clearance you are seeking or shift the BB a tad forward and split it with the length you feel you'd need to add in the stays.

Grant Petersen said...

Good report and no surprises. The chainstays...well, the common notion is that shorter makes for better climbing, but on steep climbs, shorter just makes wheelies more likely. I'd meekly suggest to the designer that he just make them halfway between your 26 and 29er chainstays. Any theoretical traction lost (by going longer than 26 chainstays) will be made up for by the 650B's bigger footprint.
I hope Haro sells tons of these, and way to go for sticking your neck out there. So much, so much more admirable than sitting on the sidelines and waiting to see which way the wind blows.
Anyway, good report, Jill.
Grant P. / Rivendell

C said...

Very, very nice writeup! I too appreciate the thoughtful open minded testing of this wheel spec. I would like to see it succeed. I am looking forward to hear others report on the qualities of the 650B ride.

wrw said...

A GREAT report!
Implementing 650B technology appears at 'first blush' to be a questionable effort.
Question: Slower, by design, is good for the typical ATB rider?
Simply, if 650B is truly worthwhile technology it will succeed on merits observed by multiple industry sources!

Rich A. said...

I'm wondering what the effects of raising the bottom bracket would be. While the wheel size might make the bike more stable, does the higher BB counteract that a little bit? If the wheels fit, can they simply be slapped onto a 26" designed frame and call it "done"? Or would new frame designs for this wheel size have the BB lowered just like a 29r's?

jill hamilton said...

In this particular test, my BB was raised a mere 1/4". Most people who have mounted 650B wheels onto 26" wheel frames have found their BB's are raised no more than about 1/2".

J. Bikegeek said...

I added 650B x 42 to my Sonix. They fit with a swap of the Front D. I had a different 9spd Deore that gave much more clearance. I too used the
Blunt rim. I build wheels at American Classic, and the 650B rim size is something we've been seriously observing. Jill, I'd like to talk with you about this bike at the show. -Jeremy Quijano, American Classic - Tech Dept.

Scott Owen said...

Great review. Maybe I am missing something, but shouldnt the bottom bracket be raised by exactly the difference in radii between the 650B and 26 wheel/tire combos? That should work out to ~3/4 of an inch.

grbe said...

Jill - have you tied just a 650B upfront and a 26" in the rear? I am reading about good results with this format (best of both worlds)without having to buy or retrofit your 26" bike for a 650B rear tire fit.

Iain said...

Speaking as an arm chair philosopher, why would the 650B sail through the part with which both the 26" and 700C had trouble? By my math, a 650B rim would be about an inch bigger than a 26" rim, and a 700C rim would be about 2.5" bigger than a 26" rim. So being between the two, why would it handle better than either on certain parts?

basslu said...

This is a great review! Have you tried any of Haro's single pivot bike like Extream X6 or Shift with 650B wheels both front and rear? I am testing Nevegal tires for Kenda here in Taiwan. I love them on my single speed hardtail. But I couldn't find any full suss bike around me that can fit 650B in the rear. I noticed that some single pivot bikes like Cannondale Proghet and Santa Cruz Heckler can fit perfectly. So I was wondering if Extream X6 and Shift can fit 650B or not? Mayby I will get one of them for my test. Thanks.

Dekoffer said...

I've been running a 650b front wheel (stans 355 rim w/american classic hub) for several months on my 2009 stumpy (talas fork) and agree completely with the review: most of the benefits of the 29er wheel size w/o any of the drawbacks. I've had absolutely no problems navigating tight corners. It really rolls noticably more smoothly and soaks up the trail chatter. With the rear 26 in wheel, climbing characteristics remain unchanged, as does gear selection.

I have noticed absolutely no negative handling characteristics due to using the 650b up front. Nothing unwelcome from the raised bottom bracket height. All positives as far as I can tell. Ultra-smooth, stable like a 29er but navigates tight turns like a 26er.

I will be tryin a rear 650b soon (which can be done on the stumpy's without making any modifications), but I expect that climbing characteristics and gear selection will change (slightly) due to the switch.

FYI: The guys at my LBS run 650's on their 2009 epics, but say you can't run a rear 650b on the 2010 carbon epics, but you still can on the aluminum ones. 2010 Stumpy's remain ready w/o modification, I'm told.