That was a bit of a mouthful...
I have been using an XTR 9 spd rear mech on my Salsa El kaboing 26" for a couple of years here in AZ. I like to ride tough techy rocky stuff, and I have been amazed at only trashing one rear mech so far. That was almost 2 years ago now. I started to get some chain skipping off the lower pulley a few weeks back, and when I looked at the pulley wheel it was very worn.
I replaced it as soon as I could with an older XT wheel from an old mech I had, but I had suffered some more off-wheel chain shenanigans in the meantime. Irritating but not a ride-ender. This replacement was hardly worn, and the exact same size as the old one.
A couple of rides into the new wheel, I started to get the same thing, and so I changed the pulley wheel again, this time for a brand new one from the LBS. When I was changing them out this time tho, I noticed a lot of wear on the inner mech plate where the chain had jumped off the wheel and rubbed the metal. In one place the edge of the plate is almost knife-edged. This had the effect of increasing the clearance between the edge of the chain and the plate, thus making it easier for the chain to skip off the wheel again in bouncier terrain, then exacerbating the problem by wearing the metal down more each time this happened.
In addition to this, the chain jumping off the pulley was pushing the wheel itself sideways on the bearing, just a little, but enough to further increase the chain/plate clearance, making it even easier for the chain to jump off. This was fast becoming a lose/lose situation!
I have bought a used mech on ebay to cannibalise for parts, which I am waiting for, and today in order to ride, I took off the mech again and moved the pulley wheel back to the center of the bearing, and wrapped the worn parts of the plate with a little electrical tape just to act as a buffer to the chain skipping off the wheel. A temporary measure, but it works!
I have been using an XTR 9 spd rear mech on my Salsa El kaboing 26" for a couple of years here in AZ. I like to ride tough techy rocky stuff, and I have been amazed at only trashing one rear mech so far. That was almost 2 years ago now. I started to get some chain skipping off the lower pulley a few weeks back, and when I looked at the pulley wheel it was very worn.
I replaced it as soon as I could with an older XT wheel from an old mech I had, but I had suffered some more off-wheel chain shenanigans in the meantime. Irritating but not a ride-ender. This replacement was hardly worn, and the exact same size as the old one.
A couple of rides into the new wheel, I started to get the same thing, and so I changed the pulley wheel again, this time for a brand new one from the LBS. When I was changing them out this time tho, I noticed a lot of wear on the inner mech plate where the chain had jumped off the wheel and rubbed the metal. In one place the edge of the plate is almost knife-edged. This had the effect of increasing the clearance between the edge of the chain and the plate, thus making it easier for the chain to skip off the wheel again in bouncier terrain, then exacerbating the problem by wearing the metal down more each time this happened.
In addition to this, the chain jumping off the pulley was pushing the wheel itself sideways on the bearing, just a little, but enough to further increase the chain/plate clearance, making it even easier for the chain to jump off. This was fast becoming a lose/lose situation!
I have bought a used mech on ebay to cannibalise for parts, which I am waiting for, and today in order to ride, I took off the mech again and moved the pulley wheel back to the center of the bearing, and wrapped the worn parts of the plate with a little electrical tape just to act as a buffer to the chain skipping off the wheel. A temporary measure, but it works!
