Originally Posted by
chapel
I'm going shopping for wheels on Monday and I wanted to know how to get 6 gears on a cassette?
Are the gears interchangeable on a cassette? is it possible to buy a 7 speed cassette, remove one of the gears and then put spacers on to fit?
I really don't want to have to get new shifters and rear derailleur and I like my indexing. I'm fine with a 6 speed right now.
Early "Uniglide" cassettes were 6-speed (and rarely, 5-speed), but I don't think that's what you're asking. 6-speed spacers were 5.5mm thick, 7-speed spacers were 5.0mm thick... -ish. In theory you could modify a more-common 7-speed cassette to work with 6 cogs and your shifters, but that's pretty advanced. Good reference:
http://sheldonbrown.com/cribsheet-spacing.html
I agree with the others: brand makes all the difference. Shimano is fairly easy, SunTour is much, much more difficult. I have no clue about Campagnolo.