Cassiel

So, the chain I put on yesterday skipped this morning as I rode home from school - skipped a lot, especially when I was mashing up hills. I looked at the cogs and it looks like some of them are definitely rounded. I am a total noob at this, and this was actually the first time I have replaced the chain on this bike (and only the second time I've ever replaced one in my life). So, I believe I have read that this kind of chain skipping and rounding on the cogs means the cassette needs replacing. The current freewheel/cassette setup (which the bike came with) is SRAM PG-950, 9-speed 12-26t. Do I need to replace the cogs with the exact same parts, and replace the whole cassette? What do I need in order to do this?

Bill Kapaun

Your symptoms certainly can be an indicator of a worn cassette. Kind of a rule of the thumb is 2 cassettes last as long as 1 chain. So if your chain was worn out, and you had never replaced a cassette, I'd say you were due.
Did you match up the new chain length to the old length?
You don't have to get EXACTLY the same brand etc. cassette. A Shimano 12-27 for example, should work fine. You can probably "fudge" a couple teeth larger. How many, depends on your R deraileur. I don't think you can go less than 12T on the small unless you have a "Compact" hub.

Cassiel

Is it possible to continue riding this way - carefully - for a bit, or will I ruin things? What surprised me was that I didn't think the chain was that worn, but I suppose it had about 1500-2000 mi on it.

operator

Check for stiff links in the chain. Then, if you can take a good, non fuzzy picture of your cassette face on so we can double check your diagnosis.

lebowitz

If you are skipping under load, I think you should not ride it like this. The chain and cassette wear together, so you are accelerating wear on the new chain.

Did you check the old chain with a chain checker for elongation or use the Sheldon Brown method https://www.sheldonbrown.com/chains.html (under Measuring Chain Wear section) to determine if it's toast?

If the cassette is worn, personally, I would ride the old chain and reserve the new one for when you can obtain and install a new cassette.

You will need a cassette lockring tool to do the cassette installation job, it's pretty easy.

Cassiel

Thanks!
I don't have a digital camera, unfortunately, so I can't provide a picture of the cogs. I wish I knew enough to really see for myself if they are worn. They don't much look it, to my eyes.
I did have a stiff link, but I don't seem able to loosen it up much - it's the link where the chain was joined. Advice? Is that enough to make the chain skip this way, by itself?

operator

You need to fix this.

P.S The previous reply posted a link to chain wear which includes a section on detailing how to look for wear on cogs.

Cassiel

Ok, according to Mr. Brown, if I have less than 1/16 wear on the chain then the sprockets should be ok. I have no eye for this. :-p But I measured the old chain (I assume this measuring method works off the bike as well?) and there is about 1/16 difference. So is it safe to bet that the cogs are ok?

Raiyn

You've got that backwards Sparky

Steve Katzman

Based upon your measurement of your old chain and the fact that you have a stiff link where you attached the new chain together, I'd bet the stiff link is the problem. Fix that before you get a new cassette.

I assume that you have a chain tool, since you state that you installed the chain yourself. Use the set of fingers on the tool that require you to back the plunger all the way back (the set that you didn't use to break or close the chain). Place the stiff link across that set of fingers and press on the pin (rivet) with some force, but not enough to push it out. Start with the opposite direction then you used to install the pin. If that doesn't work flip the tool to the other side and repeat until the link moves freely. That is how you fix a stiff link.

If that doesn't fix your problem its time to try plan B.

Cassiel

Thanks!