i hope, somebody in this forum use big/fast foot and sixpack/ac37/38 bb. I want to try to modify such a crank arm and replace the star by a bmx style freewheel (18mm wide).

It would help me to know the red measure in the attached draft, actually the distance from star center right side (opposite small chanring) to bb cup right side. Together with this information I should know the bb axle lenght and bb type (e-type dereilleur/standard).

the green measure would also be interesting to know, because maybe the road crankset with smaller q-factor could be favorited.

thanks for helping me out.