Shifting frustrations Shimano 105 STI
05-05-09, 10:35 AM
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Shifting frustrations Shimano 105 STI
The bike setup:
-9 speed Shimano 105 STI brake/shifter
-Sora short-cage rear derailleur
-9 speed Shimano 12-26 cassette
-compact crankset 50/34T
*all new cables & housings, everything professionally installed*
The problem:
When shifting up the cassette, the indexing is coming-up short. It's as though the indexing is only going 7/8 of a full shift, so I naturally get a lot of clatter in the mechanism. When shifting back down, one click is not enough to get off the biggest gear. Also coming down, it always seems to skip the 3rd cog.
Worth mentioning:
After my 7/8 of a shift, just a little tug on the shift lever (not a full click) is enough to complete the shift. Some shifts are pure perfection, some are not....it's a 50/50 proposition.
My mechanic is stumped, and yes....he IS a good wrench. Cable tension is fine and there was no rub or drag found in the cable housings when inspected.
We've covered the basics (not to mention the stuff over my head) and are now seeking ideas and opinions. This setup *should* function flawlessly.
Any help is GREATLY appreciated!
Aaron
-9 speed Shimano 105 STI brake/shifter
-Sora short-cage rear derailleur
-9 speed Shimano 12-26 cassette
-compact crankset 50/34T
*all new cables & housings, everything professionally installed*
The problem:
When shifting up the cassette, the indexing is coming-up short. It's as though the indexing is only going 7/8 of a full shift, so I naturally get a lot of clatter in the mechanism. When shifting back down, one click is not enough to get off the biggest gear. Also coming down, it always seems to skip the 3rd cog.
Worth mentioning:
After my 7/8 of a shift, just a little tug on the shift lever (not a full click) is enough to complete the shift. Some shifts are pure perfection, some are not....it's a 50/50 proposition.
My mechanic is stumped, and yes....he IS a good wrench. Cable tension is fine and there was no rub or drag found in the cable housings when inspected.
We've covered the basics (not to mention the stuff over my head) and are now seeking ideas and opinions. This setup *should* function flawlessly.
Any help is GREATLY appreciated!
Aaron
05-05-09, 10:55 AM
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My first thought is to clean out the shifters with WD40. Use plenty.
After that you may need to adjust the cable tension to the rear derailleur, although your symptoms conflict with each other so far as cable adjustments go.
Check the derailleur hanger alignment.
Check the cable routing where the cable attaches to the rear derailleur.
Was the short housing replaced just in front of the rear derailleur?
Al
After that you may need to adjust the cable tension to the rear derailleur, although your symptoms conflict with each other so far as cable adjustments go.
Check the derailleur hanger alignment.
Check the cable routing where the cable attaches to the rear derailleur.
Was the short housing replaced just in front of the rear derailleur?
Al
05-05-09, 11:28 AM
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Is the "B" adjustment screw set up correctly? https://www.parktool.com/repair/readhowto.asp?id=64 Check out Park's website for rear derailleur adjustment... it's great. It sounds to me like you need to adjust and dial-in the barrel adjuster. Getting perfect shifting is a bit of a science though. Perfect adjustment is not easy.
05-05-09, 02:19 PM
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Make sure, also, that your cassette lockring is tightened properly (40Nm=Tight)
05-05-09, 08:29 PM
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S
Sorry for the late reply, all...
I would like to sincerely thank you for thinking through the possibilities with me. Some of your ideas have been covered, some not. Here's what I'm going to do in the morning:
1. Double check derailleur hanger alignment
2. Replace derailleur cable and the short piece of housing that leads into the barrel adjuster
3. Check torque on cassette
I think all the rest has been covered....twice.
I would like to sincerely thank you for thinking through the possibilities with me. Some of your ideas have been covered, some not. Here's what I'm going to do in the morning:
1. Double check derailleur hanger alignment
2. Replace derailleur cable and the short piece of housing that leads into the barrel adjuster
3. Check torque on cassette
I think all the rest has been covered....twice.
