Observation Goin’ ’Round and ’Round

There’s a debate among bike designers these days. Or is it a discussion? Maybe it’s neither. Maybe it’s more of a silent demonstration. But it’s clearly something upon which many builders don’t agree, even with themselves: wheel size (which, naturally, requires a consideration of tire size). Everybody’s got a favorite (or two), but one size can’t do everything for everybody.

As builders refine their ideas, the good ones build demo bikes to put their experiments to the test, and, especially when it comes to the utility category, wheel size is one of the primary variables they wrestle with. Each size has its advantages and disadvantages, though you’ll find that some are more in the black than others.

There are way too many wheel sizes out there, and there’s lots of confusion surrounding them, so I’ll just talk about the ones enjoying the most favor among constructors these days, which also strike me as the most practical. Imagine a competition canvas; there’s the square kind for boxing and wrestling, the octagonal kind for mixed martial arts, but in this case it’s a triangle, with three major contenders

In this corner, the venerable 700C (622mm bead-seat diameter, per the International Organization for Standardization and the European Tyre and Rim Technical Organisation). Most race and road and cyclocross and track and fixie bikes run these, and you’ll increasingly find them on mountain bikes as well, though in that world they’re called 29ers, to more clearly peg them in the context of the standard 26-inchers with which most trail bikes are spec’d. It’s a bigger wheel, but usually it’s sporting skinny rubber (say, 23 or 25 mm), which is awesome on a smooth highway or in a velodrome but doesn’t offer much shock absorption in real-world conditions, which means you and your bike frame absorb the shock, which slows you down. Stick a fatter tire on there (I run 42mm Schwalbes on my CX bike) and it’s a different story; on the trail, bigger wheels handle terrain irregularities better. However, if you’re on the short side, 700C isn’t going to be the best choice if you’re looking for optimal bike geometry.

In this corner, there’s 650B (584mm b.s.d.), which, like 700C, is actually an old French standard. The French used this wheel size on every kind of bike for years, but it’s especially known as having been their ideal for porteurs, randonneuses, campeurs, and cyclotouristes—that is, urban utility riding; fast, mixed-terrain rambling; bike camping; and extended, unsupported touring. The beauty of 650B is that, once you slap on the fatter rubber it’s meant to take (say, 38 or 42 mm), the wheel/tire combo ends up being roughly the same size as a classic 700C wheel with a skinny tire. So you’ve got that big wheel with some serious air between you and the hard stuff down below. This has not been lost on today’s builders, and you see this size more and more on custom bikes, with lots of lovely new tire options popping up with fairly metronomic regularity. Make no mistake: this isn’t some vintage craze for nostalgia’s sake; it’s an extremely practical solution enjoying a renaissance. But, that said, it’s far from ubiquitous, so your average corner bike shop doesn’t deal with it, because the industry’s Godzillas and King Kongs aren’t dabbling in it. Yet.

In this corner, it’s the mud-stained 26-inch (559mm b.s.d.). Its inner rim diameter is 25 mm shy of 650B’s, which is 38 mm shy of 700C’s. But it, too, is meant for fat tires. (Even seriously obese ones: witness the massive 94mm hogs. Surly designed for their all-terrain Pugsley.) And of course it’s beloved by singletrack aficionadoes as their graduation tread, the big brother of BMX for all us little dirt grunts who outgrew our PK Ripper or Mongoose or nameless gaspipe sculpture back in the day. But the really cool thing about the 26? It is indeed ubiquitous. It’s everywhere, anywhere, all over the world. The global mountain-bike boom made sure of that. So… touring South America, Africa, India? You best run these, cowboy. Sure, it’s smaller, but not by that much, and when you break down in some godforsaken corner of some far-flung back of beyond, chances are there’s going to be a smithy with a stash of just what you need. Now that’s utilitarian.

Something to think about come September.

By Jeremy Spencer