Use a set screw hub in conjunction with a .770” to .625”hub adaptor to mount foamwheels to channel.
Set screw hubs offer a cheap way to attach hub mount gears or wheels to a shaft. The hub offers 4 equally spaced 6-32 tapped holes and is precision machined from 6061 T6 aluminum. The set-screw is 10-32 and uses a 3/32" hex key.