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Old 05-25-11, 07:36 PM   #1
BigK75
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Gear not immediately downshiifting

Hey Folks:

I have a 2008 Madone 5.2 that I bought used. It comes with full Ultegra gears. A couple of weeks ago I tuned it up for the first time using the Shimano instruction manual. Everything worked fine on the first couple of short rides but now I notice when I downshift it takes a second to actually downshift in the middle gears. When this happens it seems to make a noise as if the gear is skipping. Then all of the sudden it will just pop into gear. Shifting up the cassette works just fine with no problems. This seems to only happen in the middle of the cassette (gear 5, 4). Does anyone know what this might be and how I fix it?

Claude
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Old 05-25-11, 08:45 PM   #2
Al1943
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This is often caused by 1) improper cable tension, try adjusting the tension with the barrel adjuster found at the RD.
2) dirty gunked-up shifters, try hosing out the shifters with WD40
3) dirty and worn shift cables and cable housings, especially the short housing just before the rear derailleur.
You may need new shift cables and housings, always replace the housings if replacing the cables.

BTW, a downshift is going to a larger cog on a cassette or freewheel.
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Old 05-25-11, 08:54 PM   #3
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One piece of info you don't provide is if there were shifting issues prior to you making adjustments. Was your current issue occurring prior to your tune up? Or were you trying to resolve a different issue?

I wonder if the problem cogs are simply worn out now, based on the age of the bike and the problem cogs being in the center of the cassette.
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Old 05-25-11, 09:02 PM   #4
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Quote:
Originally Posted by Al1943 View Post
This is often caused by 1) improper cable tension, try adjusting the tension with the barrel adjuster found at the RD.
With head-tube or down-tube shifter boss mounted adjusters it's often simplest to finalize the tension adjustment when riding where things are a little different than on the repair stand (different cadence, etc.) Screw the adjuster in a little if it shifts to a smaller cog slower than a bigger one, screw it out if the shift to a smaller cog is faster until you arrive at the best compromise for all usable gear combinations.

If it's not possible to get good shifts across the entire cassette in all rings there's something wrong. Could be cable related, could be a bent derailleur hanger, could be worn derailleur pivots that are getting sloppy.
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Old 05-25-11, 09:21 PM   #5
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Lets confirm what 'downshift' means.

Going to an easier gear or harder?
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Old 05-27-11, 07:01 PM   #6
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I thought I would follow up on this. I did as post 2 suggested and tightened the cable tension. That fixed things beautifully

Claude
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