Fastpedaller
Well-Known Member
The difference in bb height as measure is indeed as expected very close to 2 inches, being the difference in rolling radius of the 2 tyre sizes. maybe Brompton will look at a slightly lower BB? One advantage of the larger tyre is the extra ground clearance where more gear/range dictates a longer derailleur/tensioner. With a higher bb, a really large chainring won't drag on the ground either 
