A good, rock-solid case can be made that if the bike world were to start from scratch, 650B would be the NORMAL size. Why not? It’s in between 26-inch and 700C, so it fits a wider range of bikes than either.
True, you can get dinky bikes with 700c wheels, and monster bikes with 26-inchers, but those are mismatches for all kinds of reasons, technical and visual. It’s better to do it the way we do it: Tiny bikes get 26-inch wheels. Merely small to mid-sized bikes get 650 or 700c, depending. Big bikes get 700c.
In spite of its inherent sense, up until about 2008, 650B anything was weird enough to scare 98 percent of all big manufacturers and bike riders. We were the non-chicken pioneers. So much has happened since, though, and several bike bike-, rim- and tire makers (WTB, Haro, Kenda, Continental, Schwalbe, Velocity) now offer 650B gear. It’s still the RC Cola of bike tires, but we are resolute in our support of it, because it often is the clear, smartest way to go.
Still, it’s a common concern: What if I’m touring in Timbuktu and I need a new rim-tire-wheel? We have researched this. There’s no bike shop of any kind in Timbuktu. There’s what amounts to a general store, but it doesn’t sell bike stuff. Surprise: Timbuktu is a hot, sandy place that’s inhospitable to bikes. Avoid it!
Here are the rim diameters of the three common wheel sizes, so you can see how they stack up:
700C = 622 millimeters
650B = 584 millimeters
26-in = 559 millimeters
A simple but good way to think of them (but not when communication matters, as when buying wheel parts) is large, medium, small.
700C = Large
650B = Medium
26-inch = Small
When you do that, it’s easy to see the sense of a 650B wheel. It is the medium size, and most bikes are in the middle range between big and small, so it makes sense to use a mid-sized wheel. Not just because medium goes with medium, etc, but because when you design a small frame around a 700C wheel, you have to do dumb stuff with the top tube, head tube angle, and fork offset to get the wheel out of the way. When you design a big frame around a small (26-inch) wheel, you have to make compensating compromises in either the length of the fork blades or the head tube. If you lengthen the head tube, the bike loses stiffness as it loses triangulation. If you lengthen the fork blades to keep the head tube reasonably short, you end up with a wacky out-of-proportion fork that looks horrible, and shouts out that the designer goofed, or just didn’t know.
In our case, we solve this problem by putting small to medium wheels on our small to medium bikes, and medium to large wheels on our medium to large bikes. It leads to a certain amount of confusion at first glance, because by doing this, we’re playing by different rules than most bike makers (all others?) play by. But they are better rules, even if they need explaining. Big makers have to stay the course, no matter how unsensible it is.
But a few years ago, Kirk Pacenti introduced 650B wheels to the mountain bike world, which was dominated by 26-inchers, with 700C wheels (29-inchers) a strong second place. If 650B mountain wheels (sometimes called 27 ½-inchers) didn’t make sooooooo much sense for mountain bikes, they never would have stood a chance.
As it turns out, they make tons of sense for mountain bikes. The smartest sizes or the smartest things don’t always win and sometimes don’t even succeed, but half a dozen bike makers now offer 650B mountain bikes, and half of the big tire makers do, too.
It’s not a magic tire size. It rolls over bumps better than a 26, but not as well as a 29 (700C). It turns quicker than the big wheel, less quick than the small wheel. Its proportions are better visually for mid-sized bikes than either.
Some rim-tire makers that support the size include Velocity (several rim models), Panaracer (10+ tires), Schwalbe (4 models), WTB, Continental, Kenda, and some others that don’t come to mind right now. Hutchinson---although I think they sell them only in Europe.
Point is this: 650B is a really smart size wheel for many mid-sized bikes. It won’t be widely accepted, because some people-riders-manufacturers are sticks in the mud, and/or they have a secret anti-agenda, or --- at worst --- cannot accept logic that seems so obvious. But there is enough manufacturer support for this wheels size now to assure all but the most paranoid and nervous bike riders that when the bike that makes the most sense for them happens to have 650B wheels, that should be no deal-killer. It’s likely a better-designed bike with the 650B wheels than it could have been with any other wheels.