Bicycle Mechanics - rear deraileur adjustments
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08-31-08, 07:58 PM
i recently replaced my rear dérailleur, and no matter how much i fiddle with it, i cant get it to shift properly. the shifter is a shimano deore M771 long cage. the problems that im having is that it shifts several gears at a time, and when i get to lower gears from about 4 below, my chain comes completely off and gets stuck in between the wheel and the cassette. anyone know how i should adjust the dérailleur or any tips on what needs adjusting? whether its the cable or the alignment screws?
thanks for any help given.
08-31-08, 08:00 PM
Start from scratch-
Make sure the hanger isn't bent.
09-01-08, 01:53 AM
And also make sure the shift lever is compatible with your derailer. It has to pull the cable the right amount to move the derailer one gear position and not all are compatible. As mentioned the hanger has to be parallel to the rim as well along with all the adjustments. But if the hanger is off so are all bets. Digest the Park site mentioned above - lots of good stuff there!
09-01-08, 03:35 AM
Sounds like you're mixing mid/high-level SRAM and Shimano; each use a different cable pull ratio and so are not compatible directly.
After re-reading your post, it's difficult to know which part is Shimano Deore--the shifter or derailleur? I think you really mean you replaced the "long cage" derailleur (near the gears) as opposed to the shifter (at the handlebars).
Either way, please give the brand (and model if known) of both the rear derailleur and shifter, as defined.
09-03-08, 11:11 AM
oops, ah well, it was like 2 in the morning when i wrote it.... and no, both the shifter and the derailleur are compatible, the the derialleur is a M711 and the shifter and the derialleur are mega9 compatible, so it should be ok... im guessing its just something to do with the adjustment... and i dont really have enough experience with gears to be able to adjust it properly, so thanks alot for the site that tells me what to do...
09-03-08, 02:25 PM
What shifter are you using?
I've never seen a maladjustment that could cause the thing to jump 4 gears. Do you have the derailer mounted correctly? Do you have the cable routed correctly in the shifter?
Also, it shouldn't be enough to cause the problem you're currently experiencing, but ensure that the cable is routed correctly at the derailer pinch bolt as well.
09-03-08, 02:43 PM
also if you don't have one of those spoke guards make sure your chain hasn't ground down your spokes behind the cassette.
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