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Rear Shifting Problem

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Rear Shifting Problem

Old 04-13-11, 05:45 PM
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willbur
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Rear Shifting Problem

Greetings-
I'm working on my son's 9 speed Trek. The problem is shifting from the largest to the next higher cog. It skips this cog and shifts to the next higher one out. The rest of the outward shifts are fine. Downshifts are great also-no skips.
The bike is equipped with lightly used 105 (5510) shifter, ultegra (6500) RD, ultegra(6500) cassette, new sram chain. All 9 speed. Also new cable and housing. Hanger was checked and adjusted.
Endless adjustments and substitutions of rear derailleurs have not solved the problem. Any ideas?
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Old 04-13-11, 06:44 PM
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crazyotte
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Bent cassette ring? Could be kickin the chain up to the smaller gear because it cant hold the chain for a complete rotation.
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Old 04-13-11, 06:58 PM
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liamof
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You may want to check out the youtube post. It may help if it is somethig simple.
https://www.youtube.com/watch?v=SkzvfCaIbyQ

Liam
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Old 04-13-11, 07:52 PM
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operator
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Assuming you know what you're doing and all your information about component compatibility are correct - screw the b-screw all the way in and test shifting again.

I've encountered this weird issue on some 11-34 setups on 9s.
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Old 04-14-11, 05:08 PM
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willbur
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Thanks Operator-you are a ****** genius. B screw adj did it. I thought I had it right 3/4 in (saw no jumping of the pulley when spinning backwards) but your suggestion did it. Shifts like a dream. Smooth and quiet.
BTW, the components are what I said they are and I know how to adj rear dr. I have never seen a rdr this finicky about the b screw. 12-27 have anything to do with this?
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Old 04-20-11, 06:17 PM
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willbur
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Another Question

Regarding the hanger on this bike-it is not replaceable and was alinged (sp?) by bending at the rdr mount using the Park tool. The shop guy said it was 12mm out. Since this is an aluminum frame, did this weaken it? Thoughts?
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Old 04-20-11, 06:25 PM
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jimc101
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Originally Posted by willbur View Post
The shop guy said it was 12mm out. Since this is an aluminum frame, did this weaken it? Thoughts?
That is a massive amount for any part on a bike to be out, was it 1.2mm? Suprised that an Aluminium frame does not have a replaceable hanger, if it needed the hanger to be bent by 12mm, would expect it has been weakened, 1.2mm, not so much
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Old 04-21-11, 06:59 PM
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willbur
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I think the shop guy ment 25mm at the rim. I calculate this as only about 2 degrees at the rdr mount. But will bending even this bit it weaken it?
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