Bicycle Mechanics - Rear derailer awkwardness
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05-17-12, 11:55 PM
My rear derailer is a Deore XT. I've changed the derailer hanger, and now my chain gets a little stuck between my tension pulley and the cage when I'm on the lowest sprocket and smallest chainring (so when I'm crossing the chain to the max). I didn't notice it use to do this before, is this something normal?
05-18-12, 01:27 AM
not to sound sarcastic but you shouldnt ride in that gear. instead you should be riding in the middle chainring (assuming you have 3) and about 3 cogs up, it will be almost the same. you should also avoid the opposite cross combination of the large chainring and largest cog.
but to address the rubbing/sticking obviously the deraileur is sitting in a slightly different position with the new hanger. Is it exactly the same as your old one? why did you change it was the old one damaged/crashed/bent???? did your frame bend slightly?
05-18-12, 12:23 PM
Thanks for replying. I know that one shouldn't cross his chain while riding. My old hanger was bent and I replaced it with the exact same hanger. I don't think the derailer or the frame are bent, if they are, it would only be by a very little bit.
I don't really know why this is happening. The teeth of the tension pulley look a bit worn out, so I'm suspecting that's could be a reason the chain is derailing when crossed. Could it have anything to do with the "B" screw setting on the derailer? The one that regulates how far the jockey (upper) pulley is from the hub?
05-18-12, 01:39 PM
It could be the B-screw is getting in the way of you creating the proper installation. Make sure you pivoted the RD as far clockwise as possible when mounting and tightening the bolt to the hanger. Then the B-screw will clear the stop on the hanger and then rest properly on the hanger. If you didn't, it could damage the hanger where the notch is for the B-screw. That said, make sure the chain routing is also correct. It should wrap counter-clockwise around the rear cogs, then down and around the top pulley, INSIDE the cage tab, down around the left side of the lower pulley, again, inside the cage tab.
Provided you didn't mess with the B-screw before, then it should be identical to where the RD was positioned before, unless of course, the RD geometry was altered somehow by the same thing that forced you to get a new RD hanger. Also, make sure that your RD hanger is installed correctly. If not, make sure your limit set screws are set to prevent the RD from shifting the chain past the smallest cog.
05-19-12, 07:59 AM
Hi, I solve my problem: I changed the pulleys and it worked fine. The teeth on the old one were too worn out I guess!
05-19-12, 08:24 AM
And though you threw on a new derailleur hanger,
still may not be automatically aligned, so drop by Bike shop and
make use of the alignment gage-tool.
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