650B Conversion…

By blackmountaincycles,

Filed under: 650B

I’ve got a 650B mountain bike (geared or single-speed) on the drawing board. After building a set of wheels with Kirk Pacenti’s Neo-Moto tires and Velocity Blunt rims (laced with DT 14/15 spokes to an old rebuilt King hub), I had a thought “Hmmm, wonder if these will fit in that old ti frame with the Fox F100X fork?” Sure enough, they fit like they were made for it. The crimp in the chainstay is exactly in the right spot for a 650B tire and the fork has plenty of clearance. The bottom bracket was increased by a small amount – 3/4″ to about 12 5/8″, if you calculate the difference in radius between the 27.5″ of the 650B tire and the previous 26″ tire.

For now, it was an exercise to see if it would fit, but will be a regular rider as soon as I get a chance to hit the dirt. I was planning to ride tomorrow morning, but it’s supposed to rain. Maybe Thursday… For now, here’s some photos. I don’t know if it’s correct to look at a bike as a complete package, but I look at this and think, it looks very nicely balanced and has that “just right” look.

A little comparison of a 26″ wheel bike, the 650B conversion, and a 29″ wheel bike.

1/1/08: Edit, recently Fox came out with a disclaimer against using any tires larger than 26″ in Fox Forx as they were not designed for larger tires. There are the usual nit-pickers saying that a large volume 26″ tire is almost the same size as the 27.5″ 650B tires. Yes, that is true, but the key word is “almost.” Almost doesn’t cut it here because even the biggest 26″ tire is still smaller than the 2.35 650B Neo-Moto. And yes, the 650B Neo-Moto tire does just buzz the fork crown at full compression. Converter beware.

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