Chain replaced but bottom jockey wheel “jumps”?

Question

I have a 10speed MTB and replace the chain using a powerlink. Now the bottom pulley wheel makes like a jumping kind of movement. It is not smooth. Also when in my small ring in front I get chain suck. It sucks!! I never get chain suck :(

Answer 1

The jumping is either chain friction (ie the links are not moving smoothly against each other) or links catching on teeth.

Fagan.co.za has a useful article on chain suck.

To summarise his points, the most common causes of chain suck are:

• Mud causing extra friction
• New chain with a worn chain ring
• Worn chain with a worn chain ring
• Worn chain with a new chain ring

Because the chain loads up unevenly on teeth on the bottom of the chain ring you get high friction, and the chain won't disengage properly from the teeth.

First up - clean your chain and lubricate it properly.

If the problem continues, the simplest fix is to replace the chain ring, but you could also get your teeth reprofiled to reduce the friction.

Answer 2

I'd also check for stiff links in the chain. Details of how to repair these can be found here

Answer 3

The other answers are most likely the correct solution (stiff link I'm guessing based on chain suck).

But just in case you are using the term Powerlink in a generic way...

• Wipperman chains call their link "connex" and is directional, if you put it on backward it can cause these jumps. The Wipperman Connex linkages are reusable.
• SRAM chains link is called a Powerlink and allows for easy connection and removal, but is not re-usable.

Answer 4

If you're getting chain suck on the front sprocket after replacing the chain then almost certainly the front sprocket is "hooked". Small amounts of hook just cause the jockey to jump, but larger amounts cause suck.

A rear sprocket can be cured of chain suck by replacing the chain, but the opposite is true for the front sprocket, since it's being "peeled" by the weak tension of the derailer.