Is My chain slipping?
 

Hi All,

I have a Schwinn hybrid/comfort bike that has a set of Shimano SRAM 5.0 grip shifters and a Shimano SRAM 3.0 rear derailleur. The original derailleur that belonged to this bike got damaged a couple of years ago when a branch got lodged in my rear wheel while riding.

I had the replacement derailleur installed over a year ago at a LBS. However, ever since I've had the replacement derailleur installed, I've had some problems with the bike. When I am riding the bike and putting some torque on the cranks (for example, riding up a steep hill) all of the sudden all of the resistance in the pedals/cranks seems to momentarily disappear and I hear a clunky noise, like the chian is going to derail.

Last year, I thought that the problem was an issue with the configuration of the rear derailleur. I've taken the bike to the LBS who installed it and they adjusted the derailleur a couple of times, but I still experience the problem. I've also refered to my repair manual (Bicycling Magazine's) and the Park Tool website, and I've adjusted the front and rear derailleurs (adjust the limit screws, adjust the tension, check the alignment, etc.).

I tried riding the bike again recently (after adjusting the derailleurs) and I'm still getting the problem, regardless if I increase/decrease cable tension, etc.. I mostly notice this when I'm using the smallest (inner) chainring and the lower gears (inner cogs on the rear wheel) when riding up a steep hill. The pedals will slip and it sounds sort of like its derailling, but there's no tension in the chain.

Do you think my chain might be slipping somehow when I'm pedalling? If so, how can I check to see if my chain is too long? If not, what else should I try to do to debug and fix this problem?

Thanks in advance.

There are tools to measure chain wear - Park Tools makes one. However, it sounds like maybe your freewheel/hub may be the problem. Anyone else???

... Brad

Maybe the chain got stretched in the area the branch hit?
I'd use a 12" ruler, checking the chain every 6" to see if there is any specific area that is noticeably longer than "normal".

Hi Folks,

Thanks for the replies. I checked my chain and it looked new. I took it to the LBS again and they rode it around and detected the slip as well. The mechanic thought that the cassette might have gotten damaged when the stick got lodged in the rear derailleur. They're going to replace the cassette and see if it eliminates the problem. I'll post an update once this situation gets resolved.

final update - bike shop replaced the casette and chain. it runs great now! no more slipping!

Good deal, cynergy! :)

... Brad