frisky99

Hello ,I was going over my bike and was surprised to find the idler pulley with rounded wear on the inside of the pulley. My guess would be the hanger or RD Curious how others solved this problem . No signs physical signs of damage to either. I tried to hold a straight edge to see if it is bent , but I believe the bend is original.Thank you ,frisky

fietsbob

So, flip it over to even it out..

CliffordK

Do your ride cross-chained a lot? Small rear, small front?

frisky99

I don't cross chain if I can help it and never for extended time. It is a triple and I do spend a lot of time in the middle ring. To get that much one sided wear I would have to spend a lot of time in big-big combo. The bike is 10 years old and I bought it in 2010 with maybe 3k on it and have probably doubled that mileage. As suggested I think I'll clean up and flip it and keep an eye on it . I don't remember seeing any wear after I bought it. Thanks , frisky

CliffordK

Another possibility is that the chain has hopped off the pulley, but I'd anticipate seeing some more scratching on your derailleur cage.

I think I have a 6500 or 6600 somewhere, and don't remember that much bending of the cage, although perhaps it is unclear from the photos.

Fitness Rider

I think it might be worth checking the alignment of the derailleur hanger as well as a careful inspection of the integrity of the derailleur itself. Process of elimination and if you have a derailleur hanger adjustment tool it would be a very easy check to make, as well as correct, and either confirm or eliminate it as a possible cause.

Frank

blamester

From the photos it looks like the cage is bent.
Maybe not, but if it is it's a clue.