OP probably just started another fastest thing thread hamster wheel spinning and

wont do anything with it. like so many others before..


I own the mountain drive, high is 1:1. and i don't care about theoretical speed, having a 77" high,
and it being adequate..

the recent Brompton Mk4 BB shells come to an edge, so are sort of chamfered, just not perfectly,

like if I used one of those BB cutters like Mavic required for their BB's ,
when they were competing for market share in the pro component market.

so since we are just going back and forth with dueling opinions , this thread has, likely, run its course.