Chain seems to be popping

[wolverine_1960]

Hello Everyone, Does any body know why I would be getting a loud popping noise when I try to go fast or crank down on my bike pedals really hard? It's starting to scare me pretty bad. What do I need to adjust or Fix?

[JonB]

Hi

I think you may have worn out your chain and possibly your cassette/freewheel. There's a chain-wear checker tutorial on the site, try that. If after taking the required action it's still a problem (or if you don't need to do anything) then post back, as it's quite possibly poorly adjusted gears (though I reckon worn kit is more likely)

[trevgbb]

First check that the RD is not bent, damaged or mis-aligned, then assuming the Rd is set up properly, it could be a stiff link in the chain. Set the chain on the smallest ring at the back and run the chain slowly backwards, look for jerking or jumping as it passes over the teeth and through the RD, if it does, look for a vee formation in the chain, this is the stiff link which needs to be eased using a chain riveting tool.

[Darrenjs92ni]

http://answers.yahoo.com/question/index?qid=20080808205809AAohPsJ

[Binnkin]

Not to hijack this thread but I am having the same issue.

I've got myself a Specialized Rockhopper, maybe 3 hours of use and am having a problem when I put pressure on the pedals when in 5th gear. The chain seems to bunch up and pop when I am climbing a hill or really crank on the pedals. I've adjusted the tension screw but the bike doesn't do it in any other gear.. I did purchase the bike "new" on ebay which could mean that the cassette isn't completely new and the teeth could be worn but they all look identical to the other sprockets. I took it to a bike shop on a few occasions, got a free chain out of it and had the derailleurs and other components adjusted. I also tested it in all three sprockets up front and it only does it in fifth. Any ideas would be much appreciated!

[DaveM]

"bunch up and pop" is not very descriptive. Does pop mean a noise or does the chain slip and recatch?
Regardless, first guess is a worn cassette. It's not uncommon for one particular gear to have more wear than others if the rider tends to put more miles on it. Also note that it is very hard to visually spot wear on a cassette, by the time you can see it, it's really bad. If you change the cassette, probably worth swapping the chain at the same time unfortunately. Unless the new one was just put on very recently. Usually bad to mix old cassette/new chain and vice versa.

[Binnkin]

bunching up and popping equates to the chain bunching around the top of the rear sprocket and then popping straight. it does not leave the sprocket and i dont believe it slips because the pedals keep a consistent resistance. ill see if i can get my hands on a new cassette for the rear to test your hypothesis, but as far as I am aware, the rear cassette is new.

[trevgbb]

sounds like a stiff link, see my previous post.