derailleur problem

[aicabsolut]

Yes, it will cause wear on the cassette such that a new chain will not be able to seat right on the cogs (and so your shifting and skipping issues won't improve). The next thing to go with a worn chain would be the chainrings. It's much cheaper to just replace the chain often, and if you have a really good chain (or are easy on them), you may get a ton of miles out of it before the chain wear indicator tells you to get a new one and it starts skipping. In that case, you may need a new cassette even if you don't wait until you get bad shifting or skipping problems just because of all the use. It might depend on how quickly you wear out chains and the quality or durability of the components (the most expensive cassettes don't necessarily last the longest).

[ginny]

so, what you are saying is: even if the chain stretch tool doesn't indicate that the chain is overly stretched, it isn't a bad idea to get a new chain about once a year maybe? (I probably put on about 1000 miles this year), and about 600 last year ... This is pretty much a blind guess as I don't have a computer and I really like to ride so miles don't mean much to me...

Either way, it's probably a fairly cheap diagnostic tool to get a new chain. Any suggestions to 'good' chains to buy?

Thanks for all of your help! I went for a hard hill ride yesterday, and followed my friend's advice: he told me when I was in the easiest chain rings behind to allow the front derailleur to rub a bit on the chain to keep it from skipping off. It worked. I will say that I was more ready to shift into the smallest chain ring in front than usual though.

[aicabsolut]

Well, it depends. When the biggest measurement on the chain stretch tool says it's time for a new chain, then the chain is really dead (and possibly your cassette too). It's not a bad idea to change the chain when the shorter measurement side falls through, especially if you're experiencing shifting problems.

I would look at the cables, too, though, because those will often just last a year, while a lot of chains will go a bit to a lot longer than 1600mi. Chain life will depend on your maintenance habits and riding style. You could wait until your cable goes to the point where you keep losing a lot of tension and have trouble shifting anywhere but into the little ring. Try a front derailleur cable indexing tune up. If the tune helps, then that might mean that your cable is getting old (and the problem might resume). If it doesn't help, then it is more likely your chain and the strain put on it when you crosschain.

[DebW]

Look at your shift cable housing as well. The SIS housing does fail. You may see one or more wire stands protruding from the end of the housing, past the ferrule. Or sometimes the plastic cover splits and the wires become exposed somewhere in the middle.