How do i check my bottom bracket size ? BMX.?

Question

i have a really old mongoose motivator and am thinking about buying a new frame (united magnolia), i want to use same cranks though, so how do i chech bb size.

Answer 1

take your old bike to the shop you get your new frame from, and ask them

A. is it compatible

B. can they do it for you.

if you're buying a new frame they probably won't even charge you.