I just bought a new chain like 2 months ago after the first one snapped two times. Now the new one also snapped. I’m wondering if the teeth on the cassette are too worn, or if I didn’t put the right chain tension/length.
If I need a new cassette: how can I make sure it’s compatible so I can just switch it out?
The rust on the backwheel is new and I’ll fix it soon.
by kaydeay
16 Comments
Did you properly size the chain? What was your process? The tension in the chain is provided by the derailleur. You don’t directly set the tension, although you do indirectly with chain length and to some small degree the B screw.
Was the new chain “jumping” or “skipping” when you put it on? That’s usually one way of telling if the cassette and/or chain rings are worn.
Do you start from a dead stop in high gears? Or downshift?
What chain did you buy? Can you please describe the steps you took when installing it?
ETA: The cassette teeth look fine. Also, please post a pic or 2 of the broken chain ends.
Shifting under a heavy load will definitely do that.
Do you shift gears under load?
How are you joining your chains?
A normal chain connected correctly is extremely hard to break by normal pedaling and shifting.
Something ain’t right.
Unrelated to OPs post, can you use a halflink chain for geared drivetrains?
I’ve been peddling for 30 years and I can only remember breaking a chain once. It broke because I installed it incorrectly.
Park Tools has a few simple and short instructional videos on the proper installation of chains.
[https://www.youtube.com/watch?v=O0YibMDWBAw](https://www.youtube.com/watch?v=O0YibMDWBAw)
Also, some shimano chains have to be facing the right way.
Are you buying counterfeit chains on amazon?
Overtension or improper installation/joining are likely candidates. Also could be just a crap chain.
I’m a bug guy and can put down a lot of power in a short sprint. I have snapped BB’s and rounded off square taper crank arms but I have never snapped a chain.
It looks like a ton of questions have been spammed but snapped chain is going to be something pretty hard to diagnose over the internet from a couple pictures of some chainrings and a cassette. OP didn’t describe what chain they are using or how they joined it, what happened when the chain snapped, this one is gonna’ be tough. This sounds like it’s time to bring it into a bike shop and have them do it. If it breaks again, they’re better at figuring it out.
Almost 100% likelihood you installed the chain incorrectly.
Could be many causes. The most common cause is people stopping in a small gear, then setting off again and just grinding their way along until they’re up to speed.
A lot of people point towards incorrect chain installation. So what does that mean?
When you install a new chain you will likely find a special link (quick link) or less likely a master pin included. The pins and plates in modern chain are fused together. If you try to push in the pin you partly pushed out you will encounter problems.
A good quality chain almost always break from improper installation, poor shifting technique (shifting under heavy load), or physical damage (such as chainring-ing a rock, but that would only happen with the chain on the big ring here).
As someone else requested, it would be helpful to see the broken ends of the chain.