Old Hyperglide 7-speed Compatibility, Want new 7 cassette
 

My ancient (20 year old?) mountain bike has a hyperglide 7 speed cassette. I'd like to get a 7 speed with a tighter range, like 13-24 if possible. Can I shop for any 7 speed Shimano cassette ? Or will that old hub need something specifc ? TIA

I believe that all Shimano 7 speeds have the same center to center spacing. Read this sheldon writeup on cassettes. It looks like he's saying the same thing, but don't take my word for it. =)

http://sheldonbrown.com/k7.html

-Jeremy

Really old HG freehubs also had the external UG threading and need tweaking (grinding or a spacer) to fit a cassette that starts with an 11T. Otherwise all 7-speed HG cassettes will fit. You'll probably have difficulty finding tight cassettes, though. Might be easier to just get an 8-speed cassette, sub in all your 7-speed spacers, and drop the largest cog. You could turn a 12-28 8sp into a 12-24 7-sp that way.

Good suggestion, thanks

An 8-speed cassette has narrower spacing from cog-to-cog than does 7-speed. So you'd need to either change your shifters or deal with sub-par shifting performance.

If your current cassette is hyperglide (as you say in your initial post), then it screws in with a lockring (like all modern shimano-compatible cassettes) and you can use any 7-speed cassette on the market today.
If your cassette is uniglide (in which the smallest cog also serves as the lockring and screws on from the outside) you need to figure out if your freehub is threaded on the inside as well, so it will accept a normal lockring.

I found a 13-28 7spd hyperglide cassette on eBay a couple years back, and a quick search on eBay just now revealed a 13-23 7-speed hyperglide cassette for pretty cheap.

The suggestion was to swap the spacers as well. There's another advantage to this approach, 8 speed cassettes seem to be chepaer than 7 speeds at the moment.

Ah, got it. Sorry for misunderstanding.
This solution is doable, but may be a lot of extra work of disassembling the 8-speed cassette and then using a cassette which isn't conveniently held together with rivets. And I doubt this extra effort covers the cost difference between 7 and 8 speed cassettes. However, it's a way to go if you can't find a 7-speed cassette that you want. But I think I linked one above, that's exactly what you want.

I have a stack of hyperglide 7speed cogs in my parts bin. They are all in excellent condition. PM me with an offer if you are interested.

-j

jffgreenfield<at>gmail<dot>com