Crank arm dual bicycle sprockets to motorcycle sprockets

[brone]

Hello,

I don't know exactly what these are called. Its on a Giant Stiletto bike that's used to utilize 2 chains instead of a 1 long one and attaches to where a bottom bracket would be ( dont mind the crank arm pulley I left inside ):





Questions would be if it's already a manufactured part that you could buy to attach motorcycle sprockets ( 420, 428 or gokart 219 and such).
Or is the only solutions would be to weld one?

 

[amberwolf]

I don't imagine that you'd find a MC-sprocket-compatible version of a part specifically designed to fit a bicycle component, but there could be some out there at custom shops that do stuff for the gasser bikes.

More likely you'd need to bolt or weld the MC sprockets to the existing ones on this part, or unscrew the unit to remove the bicycle sprockets, and modify the MC sprockets' cores to fit where the existing ones do. It looks like it's already coming apart so it might not be too difficult to disassemble.

Regarding part names, they may call this an idler, or a jackshaft, as two of the more common terms.

 

[Chalo]

Those look very much like regular coaster brake hub sprockets mounted on a proprietary fitting that attaches to a square taper BB. You can get those sprockets in 3/32" and 1/8" thicknesses (for multi speed and single speed chains respectively) and in sizes from 13t to 28t (but only easy to find in 16t to 22t range).

What are you trying to accomplish? A regular bike chain (or a #410 chain which is bicycle compatible) is already stronger than the other components in the drivetrain. If you're looking to beef things up by fattening the chain, you're barking up the wrong tree.

 

[brone]

Those look very much like regular coaster brake hub sprockets mounted on a proprietary fitting that attaches to a square taper BB. You can get those sprockets in 3/32" and 1/8" thicknesses (for multi speed and single speed chains respectively) and in sizes from 13t to 28t (but only easy to find in 16t to 22t range).

What are you trying to accomplish? A regular bike chain (or a #410 chain which is bicycle compatible) is already stronger than the other components in the drivetrain. If you're looking to beef things up by fattening the chain, you're barking up the wrong tree.

The vision is to completely replace this buttery aluminum part with a harder metal that would accept a keyed hole sprocket.
I think there's no other way to really do it but to take it to a machine shop and have it custom made