I was told by my mechanic that my mountain bike can fit in 29' wheel. Is it true?

As Bikeworks says there is a 38mm difference in wheel diameter which translates in a 19 mm difference in clearance given the same tire width. So measure the minimum clearance between the outside tire diameter and the frame/fork. Figure on needing a good 10mm or more of clearance in addition to that 19mm. Of course if you were thinking of running bigger wheels with a narrow tire for road riding you would gain a fair bit of clearance due to the narrow tire being smaller in outside diameter. Perhaps that is what the mechanic was referring to. This presupposes that you have disc brakes

I've seen some forks listed for both 26" and 27.5" use, but never a complete cross-over bike.

From a build perspective, t wouldn't be a problem designing a bike able to fit both sizes. But how t would handle is another matter.

Have your mechanic prove it to you. Have him mount a 29" wheel on your bike so that you can see for yourself.

As long as the wheel can spin freely in the frame and fork, everything else on the bike will work the way it is supposed to.

My bike runs a 29' wheel, it's fine, just make sure you get the right rim and tire to fit it. The rim isn't the same size as a tire.

650B is 584mm in diameter and a 29er is 622mm in diameter. Thats a 38mm difference.

I SERIOUSLY doubt that the 29er will fit even if you have disc brakes and they CERTAINLY won't if you have V brakes.

a. why do you care?

b. tell him to prove it

c. assuming you care

wle