Bicycle Mechanics - Derailleur damage question
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06-03-10, 04:05 PM
My wife and I ride the same bikes (Specialized Tricross Comps) with Ultegra derailleurs. Her chain was extremely noisy and rough today going through the rear cage so I put it on the rack to see what was up. A small tab (red arrow in photo 1) was bent into the chain line and the chain was forced to roll over it. I can't see very well with my 62 YO eyes but it looked like a small section of the tab had bent away from the rest and was poking into the chain path. I got at the thing with a vice grip and something seemed to pop off and disappear (I think that was the portion intruding into the path). I squeezed the remainder of the tab into a position that looks like the tab curves in about the same as the one on my bike (red arrow in photo 2). It shifts smoothly now so I am inclined to just let it go for now and see how it does. Does anyone think there is anything to worry about? Also, is that tab intended to keep the chain from moving vertically and popping out of the intended path?
As a side issue, those pulleys look pretty gross. Do most of you periodically clean them with a small brush or does the grime not matter a lot?
Thanks for any help.
I have no clue what might have caused the problem.
As for your filthy bits -- uhh -- bike bits, the grunge really isn't a performance issue. But at some point it has to become a pride issue! You don't have to disassemble the thing and rebuild it. But could you at least take a brush and expose the chrome?
Looks like you broke the very end of that tab off. I would not worry about it. I would be cleaning the chain, the pulleys and the derailleur.
06-04-10, 09:57 PM
Yeah, I would bust out the full strength simple green on those pulleys. The chain can and does pick up crap from there, so while it likely won't make shifting poorer, it contributes to the gunking up of the chain, which does make a racket and cause premature wear. I clean my pulleys probably every 2-3 weeks (depending on level of gunk) and it helps with keeping the chain cleaner, which means a quieter bike. I hate bike noise. HATE HATE HATE :)
Also what is with all the scoring on the derailleur plate? Looks like something ground against that general area right good. My derailleur has that tab, but it goes almost all the way to the inner plate, and is at a 90 degree angle with the outer plate, which means unless I have pulleys with too many teeth, it won't ever touch the chain unless I get some burly chainslap. Perhaps that tab got partially deformed/torn up from someone dragging the bike against that area (like a curb, for example).
06-05-10, 07:10 AM
Also what is with all the scoring on the derailleur plate? Looks like something ground against that general area right good... Perhaps that tab got partially deformed/torn up from someone dragging the bike against that area (like a curb, for example).It does look pretty scratched up. It seemed odd that nothing happened to the bike recently that would account for the problem. We were on our first ride after returning from a two week vacation. Something probably got whacked earlier and just moved slightly into the chain path the other day.
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