lots of roadbike cranks were used in the seventies and early eighties, so much that even campagnolo started colour annodising cranks for the bmx market. shimano made 600's for the bmx market again in a choice of colours, sugino, sr, stronglight etc. all used in bmx, i have 600's on my very early laserlite, mongoose had dura ace on their team goose, lifted direct form road bikes. VX and super maxy were also used on road bikes. A lot of the time, the quality and finish of the road bike parts, campy hubs and cranks, bb's and headsets, shimano stuff too was far superior to anything for bmx. 401's were an expensive buy compared to alloy roadbike cranks.