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I've got an early 1990s Schwinn Crosscut with Shimano Exage LX400 components. I've just pulled it out of storage. The bike is in pretty good shape overall. The derailleurs are moving freely and the gears and cranks don't have any significant visible wear.

The front shifter ratchet mechanism was stuck. I couldn't get in very well but i sprayed it down with WD-40 and tried to work the mechanism, but no luck.

I replaced it with a Shimano Altus SL-M310. that is working mostly, I've got it adjusted to the point that the chain rubs slightly on the front derailleur when on both the smallest crank and rear gear, I can live with that.

Meanwhile, the rear shifter failed while I was testing the new front shifter. Similar ratchet mechanism stuck.

I can easily enough (hah) replace the front shifter with the matching right side SL-M310, but with 7 speeds instead of 3 there's a lot less room for error. Is this new shifter likely to have the same distance between gears as the old derailleur?

  • Are the original shifters indexed? – Argenti Apparatus Aug 10 '18 at 16:37
  • Do consider soaking the old shifters in solvent for a while - standard problem is the grease congeals and prevents the pawls and indents from working. Patience and Solvent is required, and somewhere outside to work! Search the site - we have a number of such questions already. – Criggie Aug 11 '18 at 8:52
  • I did google for the problem when i had it originally on the front shifter, but didn't specifically search here. Lots of discussion about the lube seizing up, not so much about the solution- only suggestions I saw were to spray wd-40 in there, which I did without success. I will try soaking. What kind of solvent would you recommend? – Dan Pritts Aug 11 '18 at 19:31
  • The original shifters are indexed. I thought it was obvious since I mentioned the ratchet mechanism, clearly I was wrong. – Dan Pritts Aug 11 '18 at 19:35
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For the shifter to match, you need to match the number of speeds, cassette width and shifter actuation ratio. For Shimano everything under 10 speeds (except 8-speed Dura Ace which most people don't have to care about) has the same actuation ratio, so all you need to know is the new shifters are 7-speed Shimano. These can still be bought.

  • This is the answer I wanted to provide but was unsure if the Shimano '10 and below' actuation ratio held back to early 1990s – Argenti Apparatus Aug 10 '18 at 19:33

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