Cycling UK Forum

As a result of saving a tenner I recently got a 7 speed (Shimano) rear wheel. How I wish I'd pushed the boat out that little bit more! I'm having difficulty finding a cheap option for some 7 speed STIs and have been looking at other options:

According to what I've picked up, a Shimano 7spd STI and 7spd cassette/mech have a pitch of 5.00; a Shimano 8speed STI will work with a Shimano 7 speed cassette/mech with a pitch of 4.80; a Campag 9 speed ergo will work with a Shimano 7 speed cassette/mech with a pitch of 5.26.

Hmm, so, according to the excellent page here a Campag 10 speed mech should work with a Shimano given a pitch of 4.79?

Or have I got it all wrong?

According to this table the only Shimergo combination that matches near enough the 5.0 mm pitch of a 7-speed cassette, is an old (pre 2001) Campag 9-speed Ergo shifter with a hubbub modified Shimano rear mech.

You can convert a current 10-speed Ergo into an old 9-speed by swapping the indexing cam, but that's a tricky operation best left to an expert (such as Jeff Bowler at Mercian Cycles).

Another (simpler) option is to swap the spacers in a 7-speed cassette for those salvaged from a worn-out 8-speed cassette. Remove and discard the rivets or bolts that are merely a convenience to hold the sprockets together. The top sprocket has a non-removable spacer, but it doesn't matter if that one's differently spaced.

You now have have a 7-speed cassette with 8-speed spacing. You'll need to place a 1mm washer behind it to take up the difference in overall width on the freewheel body. This cassette will be indexed perfectly without any further modifications, by a Campag 10-speed Ergo and Shimano mech.