Been a roadie since my first 10 speed when I was about 9-10. However, I'm going to put together a BMX for my kid. Just scored a NOS frame for little $. It has a BB for an Ashtabula crank. I plan to put in an adapter for a 3 piece. What length is a "typical" BMX crankarm? She'll ride primarily on the street and it'll be a freewheel. What size chainwheel/freewheel do you guys recommend? I guess BMX uses sidepulls as I don't see any cantilever mounts. What's the good stuff with BMX brakes? Basically I want to put together a bombproof streetbike for my kid who thinks "dirtbikes" look cool. Who knows maybe she'll race?