Nevermind...I just found out search is working again and found this thread.
I just purchased an old mtn bike and it has what appears to be a 7-spd cassette (has a lockring on it just like my other cassettes...I think this is different than a freewheel). Spacing is 135. Anyway, the wheels are cheap and heavy so I wanted to upgrade and leave these for winter duty. My question is this: can I put a 7-spd cassette on an 8/9 speed hub? If not, I think I need to find a 7-speed 135 mm spaced hub.
'''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
Yep, you can get a 4.5 mm spacer that lets you use a 7-speed cassette on an 8/9/10-speed hub. The only problem may be that the heads of the rivets or bolts holding the cassette together may interfere with the spacer and not let the lockring seat properly. In that case, you can do one of two things;
1)Remove the bolts or rivets and put the spacer on the freehub first followed by the cassette.
2) Install the cassette first then add the spacer between the smallest cog and the lockring. This is what I did on my old Trek rain bike when I replaced the 7-speed wheel with an 8/9-speed wheel and it works fine.