Originally Posted by
desconhecido
Save your spacers. If you take 8 cogs from a 9-speed cassette and use 7 8-speed spacers it should work with your 8 speed shifters. Doing likewise with 7 cogs and 7 speed spacers, you'll be off by .21 mm on the one and seven sprocket if the 4 sprocket is spot on. Shouldn't that work?
I pulled the large cog off a 8 speed cassette I had laying around and put it on a 7 speed hub and my RSX setup seemed to shift it fine. I need to take the time to play with it more, but it might be an option.