Originally Posted by
Wogster
I think it would be better to build a freewheel/cassette adapter, then we could simply use cassettes.... Wouldn't help for 5 speed and 6 speed, although if you took a 7 speed apart you could build a 5 speed or 6 speed out of the parts.
An adapter won't work dimensionally. The freewheel thread on the hub is about the same size as the freehub splines, and so there's nowhere to put the adapter between them. The freewheel cogs need splines or threads that are much larger diameter. All in all it would just be easier to get a freehub wheel and use the cassette as intended, which gives you a stronger axle and better indexing anyhow.
Ultra 6-on-5, and 7-on-6 speed frankenfreewheels also wouldn't work dimensionally due to steps in the splines on the freewheel body that must line up with the cog spacing.