Originally Posted by
subgrade
Someone correct if I'm wrong, but I've never come across 29 inch bicycle wheels. 29 inches refers to the approximate tire outside diameter, but 29er tires use the same 622mm diameter rims as 28 inch/700C tires do (width may differ though).
As for fat bikes, as far as I know, they have the same rim diameter as regular 26 inch tires (559mm), but the outside tire diameter of the 4 inch tire comes to roughly the same as regular 29 inch tire.
Yeah, mostly true.
Part of the reason we have a mess with 26" (and some other tire sizes) is the 26" refers to the outer size of the tire.
So far 29" has been defined as using a 622mm bsd rim.
And a 26" Fat Bike is defined as using a 559mm bsd rim.
Hopefully someone doesn't come along and redefine the sizes... well, just because.