Spacer inside a Shimano 7 speed cassette?

munkyrider

I'm swapping out an old HG-50 7 speed cassette (13-30T) from my 1992 Kona Lava Dome, and replacing it with an HG-41 7 speed (11T-28T).

The old cassette has 1-6 riveted then a loose spacer (about 1.2mm thick by my calipers) and the 13T sprocket is separate. The 13T sprocket is open ended wrt the splines so it tightens down OK with the lockring.

The new HG-41 cassette has no loose spacer (the 7th sprocket has built in spacing), and is NOT open-ended wrt the splines. When I tighten up the lockring, the 7th sprocket 'bottoms out' on the end of the splines and does not tighten against the rest of the cassette (by about a half millimetre I think), leaving a very wobbly cassette.

If I use the loose spacer from the old cassette, and slip this onto the freehub BEFORE the new cassette, this seems to push everything to about the right place, although I'll obviously have to adjust the derailleurs to suit, but this preserves the correct spacing between the sprockets.

Is this the right approach?

steve_sordy

Whatever works works. But you may also have to alter the positioning of the spacers on the BB to get the chain coming off the middle front ring to be in line with the the middle of the cassette. Ride it first though to see if the shifting works OK (after you've adjusted the mech).

munkyrider

Thanks Steve, I'll put it all together and check out the alignment.