Hi,

I've searched and searched and while maybe I haven't done the best job, I'm at wit's end. I bought an older bike (1992) with a 7 speed RX100 drivetrain. It has indexed downtube shifters and the rear derailleur spring is no longer strong enough to pull the derailleur all the way down to the smallest cog. Rather than tearing the derailleur apart and trying to replace the sprint, I'd like to just replace it. My question is, will a modern derailleur work with the indexing of my downtube shifters? I read that a derailleur really isn't speed specific - it travels the same amount of distance no matter what. So my question is, what creates these indexes? Is it a function solely of the shifter, or is there something else I'm missing? It would seem like I could get any newer derailleur and it should work fine with my 7 speed cassette. Is this true?

If not, then I really don't know what to do. The RX100 ones are hard to find, especially NOS. I'd hate to think I'm out of luck

Thanks so much for any insight anyone has.

-Collin-