Experiments in 650b

If anyone is looking for “narrower” 650b MTB tyres to fit into a CX Frame, I’ve been doing a few experiments and I thought I’d give some feedback.

I have a Van Dessel G&T, with a disc fork and fairly average looking clearance. As a guide, I can fit a 700×41 Knard in all my CX frames (Ridley X Night, Singular Kite and the VanD).

All sizes were measured on tyres with tubes at 35psi. I may go tubeless eventually but, as you can probably understand, I’ve been swapping tyres a lot recently…

Maxxis Pace (labelled as 1.95) sizes up way smaller than that. On my cheapo Crossmax rims they’re around 46mm.

Compass Horizons (47mm) size up at 47mm.

Panaracer Comet 2.0 come in at 49mm

Specialized Ground Control 2.1 is about the same, at 49mm

Why would you want to do this? Well, for off road touring 35mm CX tyres with a fully laden bikepacking rig might not be the most comfortable ride. I started looking because I wanted to ride my drop bar bike all summer as I am a crap descender, and wanted to get a bit sideways in the drops without the risk of puncturing. Also, a lot of the off-road riding up here consists of estate tracks and forestry/windfarm access roads, although there’s plenty wilder stuff too.

So if you’re looking for a cheap drop bar MTB for summer exploration and bikepacking and have a CX bike, try and hook yourself up with a mate who has a pair of 650b wheels you can try out. In my experience, clearance at the rear chainstays is usually the issue on CX bikes. The Horizons make for a great road/gravel wheel (and look boss) but they do like to get sideways in the mud, while the Comets are pretty like the WTB Nano, but with more volume. I’ve just fitted the Pace, so will feedback how that goes. And if anyone wants the Ground Controls, they don’t fit so make me an offer!


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