Gotte

I have an oldish Altus rear deraillieur that has an irritating habit of not changing down on a couple of gears until, that is, I put greater pressure on the pedals, then it jumps. I've tried new cabling, even a different changer, but the problem persists. I'm wondering if it's a slackening of the spring, and if so, how I can tighten it. ANyone have an thoughts?

FlatFender

if its the spring, you tighten it by buying a new der.

Gotte

That's a shame, such a little thing and I have to buy a new der.

DMF 

Got $10?

TreeUnit

might be a cable housing problem. A dent in the housing will cause the derailleur to shift more slowly

Bill Kapaun

Altus is pretty much bottom end, quality wise. If it has a lot of miles on it, it may have done everything it could.
Have you tried cable tension adjustment? IS the chain longer than it should be?

vpiuva

I think if you disassemble it you'll see a second hole at the bottom pivot that will tighten the spring slightly.

tellyho

It seems obvious, but have you oiled the pivots?

Gotte

Thanks for the help. I haven;t oiled the pivots in a while, thinking about it, so I'll try that, and the second spring hole, which I think is what I'm looking for. I know it's bottom end, and old, but it hasn;t actually done that many miles. Call me cheap, but I don;t like to throw stuff when I can fix it.

mlh122

You can find the spring, maybe try all your LBSs or a local bike collective if you have one. Actually at a local bike collective you might be able to find a cheap replacement entire Der. for $4. if you can't find one locally, you could probably find it through hours and hours of googling, but when you add up those hours and the cost of the spring plus shipping, you might as well get a new der. Altus level stuff isn't that expensive, you could even upgrade a little and get an Acera, Alivio, or Deore.

I had a similar problem with a shifter that I had damaged slightly in a wreck, it would shift all the gears, but I could never get it quite right. The arm was bent a little and tweaked the innards so it was just off a little. i took it apart and tried for quite a while to bend stuff back into place, then I gave up and got a nice used Deore shifter on ebay for $11 including shipping, works great

Gotte

You know, thinking about it, you're right. Off to the bike shop I go...again.