Background I have an 8 speed 26" freehub/cassette based wheel on my MTB. It runs a 7 speed MTB cassette with a spacer and 7 speed shifter. It works fine.
I also own a 20" folding bike that has a 6 speed freewheel. I wish to increase the gear range from the current 14-28 freewheel to both larger and smaller. However 6speed freewheels are expensive and only available in 14-28 or very similar ranges.
I also have a loose hub with a 7 speed freehub.
My plan is to put the 7 speed hub onto the MTB and use the 8 speed hub on the folder, with a new wide-range MTB cassette like an 11-32 or 11-34 and a new 8 speed shifter.
I understand that the folder's 20" wheel needs a complete rebuild onto a cassette-based freehub hub.
Question Do I have to take the 8 speed hub from the MTB wheel (meaning two complete wheel rebuilds) or can I swap the 7 and 8 speed freehub bodies off the hub, which will mean only one wheel rebuild ?
Similar to Can I replace a 9spd freehub with a 7spd one? but not quite the same