i dont know why no one has put an Alfine or Rholoff system into a BB yet.
the answer i normally get it "it wont fit" but cannondale are using BB30, theres bmx sized standards.
make it bloody fit!
i would put the freewheel mechanism in thier too, so the rear sprocket is a bolt on fixed cog.
now THAT i would buy.
screw in, forget till it explodes, replace.
mechs are beautiful bits of engineering
long may they reign, or until i get my BB gears out at least.