Bicycle Mechanics - chain keeps breaking

Ok, I got a mechanics question. I attended a chain maintenance seminar a while back. I got excited with my new skills and replaced the chain(it was actually stretched, I never knew that).

While replacing it, I noticed that my granny gear chain ring had a bent tooth, and worn unevenly. It answered the puzzling question of why my chain would always hang-up when shifting to granny under load. I straightened the tooth out, and put the chain on. All cool. Except that, my new chain has since broken on me twice now!

Am I doing something wrong with the install? Pushing the link too far, not far enough? I swear it looks good when I put it in. Or maybe the messed up tooth is screwing up the new chain? It didn't break the old chain when it was totally bent.

I've never had a factory installed chain break, now I put a chain on for the first time and it's broken twice in 2 months.

Ideas?

Last season, I rode with someone who seemed to have their chain break every few miles or so. You would hear a "ping", the guy riding grunt as he hit the stem, and then a bunch of grinding as the chain went through the derrailleur and came out on the ground. We never really did find out why that was happening. He even had other people reinstall the rivet (which had often flown off into the woods and was miraculously found), and it still happened. The problem was that the rivet was just popping right out of its hole and shooting off into the woods. He eventually got a new bike anyways, fixing the problem. Make sure the chain is the correct length, there are no tight links, and it is cleaned/lubed. Have someone else who knows what they are doing put the rivet in or look at it after you're done to make sure it looks correct. Other than that, I would just advise grabbing a new chain.

-Moab

If this is the same chain, that broth both times I would replace it. Possibility you just got a bad chain. I would suggest a SRAM one with a power link, is so much easier to install the chain :)

Originally posted by moabrider47
He even had other people reinstall the rivet (which had often flown off into the woods and was miraculously found), and it still happened. The problem was that the rivet was just popping right out of its hole and shooting off into the woods.


The problem was actually you were installing the same rivet every time, which is a very very big no no.....every time you pressed it in again the hole got bigger and bigger. The best thing to do is get a quick link to fix a broken chain, once you start pressing pins out of a chain your going to have problems.

Kev, yea it is the same chain. SRAM, I had to look that one up, but it looks pretty sweet. But what if you're out and about, and one of the other links does break? Does it work the same as normal chains? Or do you carry spare power links? I'll check it out.

Thanks for the info.

You can carry spare powerlinks if you want, or you can use a chain tool to fix it either way will work. Normaly the weakest point in the chain is where you connect it up, sicne like klein said it actualy makes the hole larger when you reinsert the rivet. So chances of braking should be less with the powerlinks. Wipperman also makes chains with same type of connector. I just said SRAM as a example.

Cranky: how many speeds does your bike have?

As a general rule I keep a spare Powerlink availiable at all times.

You should never reuse pins if you can help it. Many newer chains require that you use a special pin to join the chain and you only use it once. As others suggested, carrying a spare Powerlink or two would be a good thing, along with a handful of connecting pins if your chain requires them.

The dilemna with my SRAM PC-89R (slotted link road chain) is not with the pins but with fractures across the forward end of the link plates (not at the slotted middle part.) I've suffered three broken links in the last six months. The original chain has 4000 miles on it so I purchased new replacements (my bent has an 11-foot chain so it requires three :eek: ) I didn't have shifting problems so I don't suspect chain stretch but I do tend to mash in the big chainwheel (I thrive on speed). Maybe I'm pushing my luck so I plan to install the new chains soon. Has anyone had multiple link fractures like this?

A mate broke a PC-48 chain the other day, from the pin hole to the end of the plate. I thought this was very strange, but may have had something to do with him needing a new cassette, as the chain skips under high load. The chain is 3-4 weeks old.

I use a sram PC-49 on my mtb and I carry spare powerlinks, but have had no failures (my first SRAM, although I used Sachs/Sedis chains exclusively on my roadbikes years ago). I have only ever broken one ShimaNo chain, and it just came apart, I think from old age.

In the granny ring which you "fixed", were the bent and worn teeth the pre-worn and pre-bent teeth which you find on new chainrings?

MichaelW,

Ah yes, a very good question. Well this was my first chain and chain-ring experience, I normally don't bother with this kind of stuff but now I want to learn. I did take it down to my LBS to buy a replacement, but he didn't have the part. Apparently Cannondale chose to use a non-standard chain-ring for the granny. It isn't completely flat like normal ones. The position of the ring is offset from the mount. He said, "maybe" it could be fixed with spacers and it started sounding hokey. I decided to just bend the tooth back and call Cannondale dealers to see if they carry the part. Apparently not soon enough.