Setting up Shimano rear der starting position
09-17-18, 06:07 AM
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Setting up Shimano rear der starting position
I seem to recall back in the day (of early Shimano S.I.S.) when I read the instruction sheet for my 105 6-speed rear derailleur that the high gear position involved lining up the center line of the top pulley lining up with an imaginary line extended down from the start of the smallest cassette cog. Not the centerline of the smallest cassette cog. My understanding was that this in someway aided upshifting. The Centeron pulley would allow proper indexing across the cassette. It worked on my 6 & 7 speed index set-ups.
I’ve been setting up my 9x3 Ultegra 6500 GS/Dura Ace 7703 using the same assumption. But my shifting across my 12-23 9-speed rear cassette is off just a bit. My housing and stainless cable are new from last year (Jagwire LE-X). When I get things centered well on the low cogs, I have to pull my cable below the down tube stop while riding to get that last tenth of a millimeter to allow it to upshift.
Am I due for a refresher on rear derailleur set-up on Park Tool.com?
I’ve been setting up my 9x3 Ultegra 6500 GS/Dura Ace 7703 using the same assumption. But my shifting across my 12-23 9-speed rear cassette is off just a bit. My housing and stainless cable are new from last year (Jagwire LE-X). When I get things centered well on the low cogs, I have to pull my cable below the down tube stop while riding to get that last tenth of a millimeter to allow it to upshift.
Am I due for a refresher on rear derailleur set-up on Park Tool.com?
09-17-18, 07:18 AM
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Sounds like you need to add a little more cable tension by turning the barrel adjuster counter clockwise a half a turn or so.
09-17-18, 08:34 AM
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Whenever I encounter a rear shifting issue that doesn't respond to normal tuning the first thing that I do is to check the derailleur hanger alignment. Most times, that's the problem. 9-speed and above cassettes have the cogs spaced much more closely than on other bikes. Consequently they are much more sensitive to correct hanger alignment.
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09-17-18, 09:47 AM
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Aligning to the outer edge of the small cog is still Shimano's recommended setup procedure in all cases I'm aware of. I would bet your der hanger is bent, your derailleur is bent, or there is some friction in the cable/housing (even i it was replaced semi recently).
09-17-18, 03:13 PM
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The Park procedure, which I recommend, does not use visual alignment but rather shifting performance, which is what really matters. Of course the derailleur and hanger need to be straight and the system friction low for any tuning scheme to work.
https://www.parktool.com/blog/repair...eur-adjustment
https://www.parktool.com/blog/repair...eur-adjustment
09-19-18, 09:49 AM
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I aligned mine with the middle of the smallest cog. Didn't realise that it's not textbook method. Lol. Anyway i was trained in Park Tool method but don't refer to it when setting up, just screwing in and out depending on the shifting precision.
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