Originally Posted by
SkyDog75
The Z50 is smidge narrower than the Z30 -- half a millimeter to be precise -- as it's designed for 6 & 7 speed drivetrains instead of 5. Older bikes with 5-speed freewheels and friction shifting are pretty forgiving, so either will almost certainly work fine on your bike.
Thanks, this is pretty useful as I may get a 6 speed freewheel latter down the road. Just need it to work for the rest of the school year.