framebuilding question about u-brake pivot locations
i'm working on my first framebuilding project -- a bmx freestyle frame -- & was wondering if any of you could point me toward information regarding the "official" locations for u brake mounts (dia compe 990 style).
specifically, i'm looking for:
1. the side-to-side distance between the centers of the studs next to each other.
2. for 20" bmx wheels, the distance bewtween the axle centerline & the centerline of the pair of studs.
i've measured a bunch of frames & forks & can come up with an average, but i'd like to use the "official" figure, if possible. i'd imagine either diacompe or shimano have published this info somewhere.