Originally Posted by
andreakane
Sorry if this is a dumb question, but I've commonly heard 650b as a good size for touring? Why is that, simply because of the wider tire options? I own a pair of 650b's myself, but always wondered if there is a difference between that and a 700c x 38 per se.
650B is a slightly smaller wheel which, when equipped with 2" wide tires, will roughly equate to the same outer tire circumference as a narrower 32-40mm 700c tire. This keeps overall geometry basically the same. Trading wheel for sidewall.
700c wheels that use 2" or wider tires exist, they are rather frustratingly referred to as "29'ers" because marketing. In fact both 700c and 29'er wheels are actually 622mm in diameter, with 28/32mm wide road bike tires in that rim size roughly figuring out to 700mm in overall diameter. The bigger, fatter 29'er tires usually bump that up to a nominal 29" or ~736mm overall tire diameter.
Equally frustrating is that 650B wheels are basically the same as 27.5 MTB wheels, both share a rim diameter of 584mm. 650B is to 27.5, as 700C is to 29'er.
Clear as mud!