|700c Wheel on the Tamland|
Let me say right up front that neither is terrible, bad, or a wheel size that you shouldn't try. Each has their merits. That said, I have a favorite and I won't be shy about telling you about it. Now, on with the show......
I suppose I should give my background for these opinions. First of all, I have 650B experience going back over a decade. I have ridden mountain bikes, road bikes, and gravel bikes set up with 650B wheels and tires of various tread patterns and on various bicycles. Of course, I have a LOT of 700c experience going back, waaaaay back, and along with this I have ridden a lot of on road and off road 26" wheel and tire combinations. All of this is being drawn upon to formulate these opinions. Basically, I have had enough time on all of these wheels that I feel that my opinion is not lacking in experience based observations.
Despite the latest "Ride The Supple Life", or whatever the slogan is, marketing, and despite the efforts of marketing wonks, the simple truth is that 650B is basically going to end up being your "mtb-ish" wheel for gravel bikes going forward. This is for good reason. Taking into account the limitations of "gravel bikes", the 650B option allows riders to put the biggest footprint on the trail possible. Add in aggressive tread and you have, what I call, "mini-mtb" wheels. They are about 1.8" wide, and essentially turn a gravel going bike into a late 80's XC mtb bike with drop bars. This is cool, fun, and useful, if you want that sort of deal. Obviously, it is a flavor not everyone will desire, or even understand.
|The Tamland with 650B tires and wheels|
The other way I would use 650B and smoother tires is for loaded touring on roads. The wheels would be stronger, the tires fitted could be wider, more comfort might be eeked out, and again, looser gravel and dirt would't present an issue. Not that you couldn't do a wider 700c tire, but keep in mind, some of these "dual wheel size" gravel rigs are limited to 42mm-45mm tires. That may not be big enough for some. There could be an argument made that says it doesn't matter with the wheel strength thing too, but I'm giving the nod here to smaller wheels.
In fact, you could make a really stout case for 26" wheels and loaded touring. Especially "world touring", but I won't get into all the why and why nots about that. Just know that 26" isn't dead in that area of cycling. Almost all my loaded touring experiences were on 26" wheels.
|650B gravel rigs are very reminiscent of this 80's era Ibis. Image courtesy of VintageMTBworkshop.com|
As far as ride quality goes, a thing many 650B enthusiasts like to hang their hat on, I'm not pickin' up what they are layin' down. 700c is every bit as smooth if you have quality tires and wheels as 650B is. All things relatively equal, that is. Of course, a 700c X 28 at 100psi is not going to feel as smooth and pillowy as a 650B X 47mm tire. However, I have a 700c X 42 set of tires on some wheels here I'd put up against anything 650B for smoothness. So, "supple life" can be had in bigger diameters.
So, which wheels should you get? My advice would be that if you are going to ride wide open gravel roads, maybe some pavement, and if you'd never consider loaded touring, single track drop bar bike action, and would never ride in adverse, softer conditions, stick with 700c. Otherwise, get both sizes. My ideal set up is going to be a 650B tire with some tooth to it for single track/dirt/looser stuff and 700c the rest of the time. Almost every inch of in-town trail here could be easily tackled, when it is dry, with a drop bar mtb bike. Slapping on some "mini-mtb" 650B wheels and tires would be great for doing that activity here. I might do smoother tread 650B in Spring around here when things are softer and 700c tires tend to push into the softer road ways. But that kind of condition is only about two weeks out of the year, so........maybe not so much. I will say that 650B X 47mm was a boon when it was like that last Spring around here. So, it is a viable option when things are wetter and/or looser and deep.
But yeah, I'm primarily going to opt for 700c most of the time for gravel travel.