Hi, we usually use 10mm Key Hubs (
http://www.andymark.com/product-p/am-0985a.htm) and attach them straight to a wheel. If you plan on attaching to a shaft, what I recommend is connecting the motor to the shaft via some #25 chain. (2 of
http://www.andymark.com/product-p/am-2182.htm and
http://www.andymark.com/product-p/am-0370.htm) You will need to have some machine keys too and the shaft (
http://www.andymark.com/product-p/am-2393.htm) on the other end will need to be milled for a keyway or you could use a grub screw.
I hope this helps.