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650b Wheels – Bikerumor’s Kirk Pacenti Interview

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For those that are unfamiliar with the 650b Mountain Bike Wheel concept, here’s the gist:  It’s a 27.5″ wheel size, smack in between 26″ standard and the 29-ers.  The idea is it allows for very similar geometry and bike layout as a 26″ frame, but with the larger rolling advantages of a 29er.  Additionally, for bikes in the 100mm to 140mm travel range, which is most full-suspension XC and Trail bikes these days, 650b keeps suspension travel in a favorable movement path versus the sometimes awkward compromises required for 29″ wheels.  It also allows for smaller riders (down to about 5’3″ tall), to enjoy the advantages of bigger wheels.

Kirk Pacenti is leading the charge to make 650b a new standard, launching his own line of tires (shown above, Pacenti Neo-Moto 2.3″) and providing manufacturers with the specs and materials needed to build 650b frames.  29ers took about seven years to really gain momentum and become a “mainstream” option.  Follow the “more” link to read the BikeRumor interview with Kirk…

BIKERUMOR: Let’s start with a list.  Who’s building 650 bikes today?


BIKERUMOR: Do you think we’ll see any 650b bikes from the big boys (ie. Trek, Fisher, Specialized, Giant) at Interbike this year?

KIRK: I don’t think we’ll see anything this year. For major bike brands, it’s not uncommon for the stuff we see today to have been in the development for a couple years. I will say that I sent some wheels and tires to Trek, Cannodale and Santa Cruz just over a year ago for testing… they are being pretty tight lipped about their findings at this point, but I’m hoping they will see some benefit in developing 650B MTB’s in the future.

The smaller companies are able to move a little faster. We will see some production bikes from the likes of Haro, Carver, Soma and Rawland among others this year. There are literally about a dozen of these small-to-mid sized companies with complete bikes in the works for 2010.

BIKERUMOR: From my conversations with a few bike shops, it seems like LBS employees generally aren’t aware of the 650b size?  How long do you think it’ll be before these bikes start showing up in shops?

KIRK: The Haro, Carver, and Rawland brands all have bikes available now. I suspect it will be another 6-12 months before there is any significant mainstream awareness about the 650B wheel at the shop level. But with all the buzz being generated on internet forums, it could be sooner.

BIKERUMOR: One of the things Trek does exceptionally well (and the reason why I own both a Fuel and a Sugar) is demo days.  Do you know of any companies out demoing their 650b bikes to generate consumer demand?

KIRK: The only company I am aware of that might do this is Ventana, through their dealer Competitive Cyclist. Ventana will also have 4 or 5 of their 650B El’ Bastardo bikes at the Dirt Demo in Vegas. Haro will probably have several of their new 650B “Beasley” MTB’s available for testing and Maverick may have some there too. 

BIKERUMOR: 29″ bikes have a cool nickname, “29-ers”.  If you could pick the slang term for 650b sized-bikes/wheels, what would it be?  Should we have a contest and the winner gets a Pacenti 650b bike?

KIRK: I thought about calling the size “27five”. I figured it was a no brainer in that it expressed a wheel size right between 26” and 29”. You wouldn’t believe the number of people who didn’t get it… I’ve settled on 650B; it’s a popular size world wide and would likely do more to generate interest abroad. But people can call it whatever they like. I’m sure whatever it’s called the name won’t win any contests!

2009 ventana el bastardo 650b mountain bike

BIKERUMOR: Let’s talk parts:  White Bros. is making forks specific to 650b, and Velocity is introducing an All-Mountain rim.  You’ve got the Panaracer-built, Pacenti-branded Neo-Moto tires.  Who else is in the game?

KIRK: Right now I have two tires, the Neo-Moto 650B x 2.3” and the Quasi-Moto 650B x 2.0”.  White Brothers is the only company currently making a 650B specific fork right now, but there are several other brands of fork that work with 650B wheels. Maverick, X-Fusion, and Cannondale Lefties all seem to accept the larger 650B wheel with little or no modification. Some forks from the big 3 will accept 650B wheels as well, but the manufacturers are not endorsing the use of theses wheels for compatibility /safety reasons.
Velocity, Sun and Stan’s are all offering 650B rims and wheels now. American Classic, Alex, WTB and Weinmann will also have rims or wheels available soon.

white bros 650b magic 100mm mountain bike suspension forkBIKERUMOR: Is there an upcoming 650b bike or component coming up that you’re really excited about?  (If your answer is a Pacenti-branded product, please also list one or two other brand products…but feel free to plug your own stuff!)

KIRK: I am excited about the other tire makers getting on board. That may sound odd, but I knew if this thing was going to take off bigger brands would have to get involved. Kenda, Schwalbe, WTB and Panaracer all reported to have 650B tires on the way. There are also a few more rim / wheel makers who may have product on display as well.

What I am really excited about though is all 3 of the big fork makers are open to building 650B compatible forks. One of them is trying to get it done this year, but it looks like it may be 2010 before we see something from the other two. 

BIKERUMOR: Mavic and Shimano just recently introduced lighter weight, XC wheelsets in 29″ size.  How long do you think before we see weight-conscious racing type products in the 650 size?  Has Mavic shown interest?

KIRK: I have not been in contact with Mavic, but I have discussed it with Shimano. It be a while before we see anything from these companies. They operate on volume and the demand simply isn’t large enough yet for them to get involved. The great thing about rims is that it’s pretty simple to roll any size you want simply by calibrating the rolling machine. Again, the smaller brands will be first to market; they typically can react faster to new niches and do smaller production runs.

BIKERUMOR: Let’s say I’m a small frame builder.  Is there open source spec material available to use in designing a 650b bike?

KIRK: As far as frame design goes, it’s just a matter of adjusting the frame specs to accommodate the wheel size. If you started with a 26” frame design, you might lower the BB a little and maybe steepen the head angle a bit.  In some cases you might have to lengthen the chainstays too, but standard 16.75” – 17.00” stays seems to work fine more often than not.

BIKERUMOR: Other than frame, wheels and fork, is there anything else that would be different on a 650b bike?

KIRK: Nope. Any off the shelf MTB part will work on a 650B bike.

BIKERUMOR: Obviously, you’re a big fan of 650b.  Are there any drawbacks to this size?

KIRK: Performance wise, I have yet to find a drawback; seriously, there’s just no downside to this wheel. You’re getting the biggest wheel possible in a frame with “standard” geometry resulting in a very compact, tight handling bike.

The only ‘drawback’ right now is lack of selection when it comes to parts, but that is changing almost overnight. Remember, from day one the Pacenti Neo-Moto, the White Brother’s Magic and Fluid forks and Velocity rims were all readily available. And by happy coincidence, may stock 26” frames and forks accept 650B wheels too. Riders have been finding some ingenious ways around the parts problem.

BIKERUMOR: What are some good online resources where consumers can learn more about the 650b wheel size?

 http://www.bikelugs.com (Kirk’s website)







BIKERUMOR: Kirk, thank you very much for the interview!

Ahrens’ 650b mountain bike (above) and one of three stainless 650b prototypes from IF Bikes (below).

Below is the 650b Diesel singlespeed from Sycip.

…and a custom Lynskey 650b bike.  This bike has Industry 9 wheels, which suggests that you’ll be able to get on the waiting list for some 650b wheels from the guys in Asheville, NC, pretty soon.

lynskey 650b mountain bike

And one from Engin (pronounced “engine” in case you didn’t know…I didn’t).

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15 years ago

Come on… give me a break. You want me to have to stock 26″, 650c, and 29er tires, tubes, wheels, etc? For the small difference it will make just blow ’em off!

15 years ago

I ride a Titus Racer X (Hammerhead version) and a steel hardtail 29er and love them both. If you could marry the 2 bikes, IMHO you’ve have the perfect bike – a 4-5 in travel 650b Pivot Cycles mountain machine

15 years ago

bikegawd – 09/18/08 – 2:11pm
“Come on… give me a break. You want me to have to stock 26″, 650c, and 29er tires, tubes, wheels, etc? For the small difference it will make just blow ‘em off!”

Surprisingly the 650b wheels are not a small difference in fact a much more noticeable improvement than my new shock, rear D, cranks, cassette, chain combined (money well spent, not that I couldn’t just Ebay them for 95% of what I paid if I didn’t like them.

Am shocked at all the hardtails, I thought the 650b would be great for larger wheels on FS bikes 6+ inches

15 years ago

Fantastic interview! Thanks for packing so much useful info in such a short length. God bless Kirk & Bike Rumor for great news regarding 650b.

14 years ago

I am working on convincing a local manufacture (Fetish Cycles) to modify their carbon FS to except the 650’s. So far, I’ve personally taken a few measurements in order to redesign the rear triangle. The chain stays have been lengthend to 17.45 inchs and the BB lowered an inch, we believe this will work, but we have yet to fully produce it. The front carbon triangle will remain stock to be economical, and the rear triangle will be made out of T6 aluminum for structural stiffness (Possibly scandium, it was also an option we are considering). We’re aiming to get 4-5 inches of rear wheel travel and keeping the weight down to 5lbs (w/o shock), to market towards the XC and Marathon riders. So here is the million dollar question – does this project of ours strike interest to you as a rider? We are trying to judge how large our market is before we invest heavily into further development.

Let me know what you think! The more info we recieve the better, below is my personal email.


Happy riding,


Paul in Virginia
13 years ago

I put a 650b on the front of my 2010 Trek FuelEX and am lovin’ it!

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