derailleur problem

[sundial]

Can someone post pictures of how to adjust the derailleur on a compact double? I'm a visual aids kind of girl. My LBS adjusted it on the stand but when I took it for a ride today, it's not quite right. It works fine in the large gear but when I shift to the 34 and the chain is in the middle of the cassette, it feels like it's slipping on the cassette, like it's not hitting the teeth right. The bike shop isn't exactly convenient to me. My bike is a '08 Specialized Roubaix.

[mayanorange]

http://www.youtube.com/watch?v=ngm6dr-1na0

They also have how to do the rear and a bunch of other handy videos. I figured it out watching these a few times, trying it, getting stuck, watch again, then it was easy once I got the concept.

[aicabsolut]

Can someone post pictures of how to adjust the derailleur on a compact double? I'm a visual aids kind of girl. My LBS adjusted it on the stand but when I took it for a ride today, it's not quite right. It works fine in the large gear but when I shift to the 34 and the chain is in the middle of the cassette, it feels like it's slipping on the cassette, like it's not hitting the teeth right. The bike shop isn't exactly convenient to me. My bike is a '08 Specialized Roubaix.

Sounds like it's a rear derailleur issue. It's common for it to seem ok on the stand but to start acting up under load. You probably just need a little turn of the barrel adjuster. Are there any delays in shifting one way or the other (does it keep skipping instead of shifting)? If that doesn't work, check that the B screw is set right and that the derailleur hangar isn't bent.

http://www.parktool.com/repair/readhowto.asp?id=64

(has pictures)

[ginny]

thanks guys! I will print some of these off and try to fiddle with things... I am beginning to think maybe I need a new chain - not an expensive fix at the moment, but I understand that a stretched chain can mess up the rear cassette (at least), right?

[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.

[Sardine]

Sounds like it's a rear derailleur issue. It's common for it to seem ok on the stand but to start acting up under load. You probably just need a little turn of the barrel adjuster. Are there any delays in shifting one way or the other (does it keep skipping instead of shifting)? If that doesn't work, check that the B screw is set right and that the derailleur hangar isn't bent.

http://www.parktool.com/repair/readhowto.asp?id=64

(has pictures)

Sorry to butt in but I just wanted to say 'Thank you!!' for pointing this out. Why is it so difficult to convince mechanics in bike shops that just because it worked fine on the stand, the problem may not have been solved when you factor in the stresses of real life road riding? And why is it so difficult to convince them to just ride the wretched thing around a bit so that they can see for themselves? It's really helpful to be able to dip into the knowledge and experience here. And yes, I have changed bike shops until I've found one that will listen and am about to do a maintenance course too.