Friction Roller: Where to Buy?

[physic.dude]

Where can I buy a polyurethane friction roller wheel?
It is for an electric 250 or 350 watt motor with a 1/4 inch shaft w/ flat part and reversed threads.
The roller wheel must be between 2 and 2 1/4 inch (2 1/8 perfect)

Thanks

 

[Venice Motor Bikes]

I posted on your other thread...