wagonfanatic

I've search around the forum for thirty minutes and can't seem to find help on this one.

I just installed a new chain (my first time) on my Centurion Accordo. Chain was picked up from LBS. I used a chain tool to measure it against my old chain and take out an extra link. It is a SRAM powerlink chain.

Occasionally, especially when peddling hard, the chain pops into another gear. Also, the bike doesn't always shift when I change gears. This could be an issue with the limits screws/ derailleur, but it was highlighted after I installed a new chain.

I'm torn between removing one more link from the new chain (after all, the old one was probably stretched out), but don't want to damage my new chain (if its too small, I'd stretch it, right?). The other option is to mess with the derailuer/ take it to an LBS to get tuned.

Would prefer to DIY with your help if I can! Thanks

FBinNY 

First of all, while we all talk about chain stretch, chains don't stretch like the elastic on your Jockeys. Chain stretch refers to a wear process which allows the chain links to move farther apart at the pins. In this way it's more like the stretching of a freight train as the engine pulls the slack out of the couplers one by one when pulling out.

In any case a chain stretches less than 1/2" overall over it's lifetime.

Cutting you chain won't help, and might make it too short. Shift to the big/big combination and make sure you still have enough slack to pull the lower loop forward 1" at the bottom of the chainring. Then shift to the small/small combination and see that the RD is taking up all the slack. If it meets both tests it's fine.

As to the shifting. New chains tend to have different shift properties than old ones. Partly it's because the plates may be shaped slightly differently, but also because new chains are stiffer and closer fitting on the sprockets and so are less forgiving of any error. Take the time to fine tune all the RD adjustments and you should be OK.

If not, it might be that the hanger is misaligned, but you can cross that bridge if/when you get to it.

Kimmo 

It's not your limit screws, it's the barrel adjuster. Check out adjusting rear derailers on Park Tool's website.

Another possibility is you're describing it wrong, and the chain is jumping over the cogs under load, staying in the same gear. If this is the case, your cogs are too worn for the new chain.

wagonfanatic

Okay thanks. I'll check out both of these possibilities. If its jumping, could that be because the chain is too long? Or what happens when the chain is too long?

FBinNY 

The ONLY issue with a chain that's too long is that the RD cannot take up the slack, and the lower loop sags like a possum belly.

Al1943

When comparing the new chain to the old chain, if the old chain was originally the correct length you should make the new chain have the same number of links as the old chain, not the same length, since the old chain has been stretched.
Having said that, if you are going to do your own chain replacements you need to know all of the acceptable methods of sizing the chain. When I install a new chain I check the big to big combination and the small to small combination and cut the chain so that the rear derailleur does not reach its forward or rearward limit. This way if I accidentally shift into the big to big combination there will be no damage to the rear derailleur. And if I accidentally shift into the small to small combination the rear derailleur will still hold some tension on the lower run of chain and there will be no slack chain.

wagonfanatic

Okay, all this is good to know