Sorry if the video is too dark. Every rotation the chain hops off the teeth on the chain ring. Before it raises off the chain ring It catches somewhere in the rear derailer/cassette as well.
This bike is a 2015 Trek Emonda ALR 5 with a 11 speed Shimano 105 groupset. Though ill advised everything was original for around 10k miles. I had zero issues with the drivetrain until I got a new indoor trainer with a new Cassette which is the same gear range but different brand(MICROSHIFT). Of course my worn out chain didnt like the new cassette so I got a new chain. Now it is doing what the video displays.
Does this mean the chain ring is worn out as well? The chain is a few links longer than the original. Would this cause it to hop?
The chain is routed correctly and it isn't between gears. In fact it shifts through all gears smoothly. The above happens no matter what gear I am in. I don't think it is binding up from diff link joints as every link is smooth.
by Draecath1423
7 Comments
Yes, your chainring is worn out.
Classic worn-out chainring behavior.
This is due to the worn-down teeth on the chainrings effectively making the distance between teeth a bit larger, so there is a pitch mismatch between the worn-out chainring and a brand-new un-worn (unstretched) chain, which causes the new chain to not mesh well with the worn chainring.
I replace my chain whenever it reaches 0.5% elongation to ensure my chainrings last as long as possible.
Now I know how worn chainring and new chain behave.
The chain is on backwards. Or the quick link isn’t fully engaged.
Your chain is on backwards if there is no writing on the drive side – if you look closely at your chain and there are no markings on the plates on the outer links (a chain is made up of outer links and inner links) – 11/12 speed shimano chains are directional and can cause issues like this if on backward – especially if your chainrings are otherwise not too worn.
Edited: for clarity I put the cause first
Chain could be backwards or a bent link or the master link wasn’t fully seated
Is the quick link properly closed? Does your chain have a twisted link? Is there a bent chainring tooth?
I see the first time it starts to ride up on the teeth of the chainring is right at the quick link so I would almost bet money the quick link isn’t closed all the way.
Edit: second time it does it is also right at the quick link. Close your quick link properly.
I think it’s the chain. If it was the chainring it would happen with every revolution. It happens at approximately 2 1/2 revolutions