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Old 01-31-07, 08:42 AM   #1
tonka.toy
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Shifting help please

Iím having a really annoying problem with the bike set up at the moment. Shifting up through the rear cassette is not as it should be, it sticks in gear or jumps two at a time. Shifting down through the gears is OK. Happens regardless of the chain ring.

Itís under warranty but I like to be able to fix things myself and it might not be more than wear and tear. Past experiences have not been great with the lbs they tried to replace the BB when all they needed to do was grease the pedals/crank that they had just fitted!

Do you think its an adjustment thing, bent hanger worn parts?

And sorry - I know shifting has been done to death but I canít find anything that matches this.

T.T.


The bike:
Trek SU600 new in September last year
It does about 100 road miles a week and has probably clocked up about 1500+ miles since new.
That model has an SRAM 9 speed cassette with an XT derailleur. Shimano chain but I swapped early on to an SRAM hollow pin.
Bike is cleaned weekly and re-lubed with finish line Teflon dry lubeÖ

The Problem:
Bike in the stand starting with smallest cog and largest ring
Will shift progressively 9-1 through the cassette without missing. (obviously thatís not a usual sequence but the same happens if shifting 9-4)
First up shift and the derailleur will visibly moved but not change gear. Usually get a bit of chatter.
Second up shift will now move up one gear.
Third up shift will move up one gear. And so on
Shift from 7 to 8 will jump straight to 9th gear.
Shift back down is OK.

On the Road, itís bugging me big time, I like to work up through the gear but I keep having to shift up two down one in order to select the desired gear. With hindsight this might have been getting worse since it was new Ė not sure. Occasionally it would seem that a change up was almost non existent, I just put it down to my supper smooth technique. ahem

Tried So Far:
Cleaned and lubed
Checked derailleur for sticking and free running movement Ėno problems
Checked cable for binding Ė no problems
Derailleur spring looks OK. But thatís just a visual check
Changed chain in November to hollow pin Sram
Tweaked the micro adjusters
Reset derailleur.
Tweaked micro adjusters Ė worked through the range ľ turn at a time.
Changed back to original chain (only few hundred miles old) Ė no change
The cassette looks OK / teeth donít looked hooked and the problem happens across the range even on gears that are lightly used.
The bikeís never been dropped or crashed and everything looks straight. But thatís eyeball only.
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Old 01-31-07, 08:59 AM   #2
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What do you mean by "micro adjusters"? Do you mean the limit screws? If so, they are the wrong things to tweak. It sounds like a simple cable tension adjustment is needed and that is handled by the adjusting barrel where the cable housing enters the rear derailleur.

Shift into the smallest cog. Then shift one click to the next cog. If the shift doesn't quite go, turn the adjusting barrel counterclockwise 1/2 turn. Shift back to the smallest cog and try again. Adjust the barrel until that shift is clean and quiet. That should fix it.
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Old 01-31-07, 09:25 AM   #3
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Thanks but yes that's what I mean by Micro Adjusters, Have tried the full range of adustment and been through so many how to's on the subject. Problem is when shifting up from the middle of the Cassette, the final shift 8-9 is always OK.
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Old 01-31-07, 09:22 PM   #4
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Slow hesitant shifting, especially upshifting, is usually related to the condition of the shift cables and cable housings. You can test for this by loosening the short housing found at the rear derailleur, slide the housing forward up the cable exposing the cable for lubrication. Re-attach, adjust, if you get significant improvement you need new cables and expecially new cable housings.

As you upshift, cable is released from the shifter and pulled by the derailleur's spring tension. Any excess friction within the housings will slow or impede the shift.

Al
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Old 02-05-07, 06:36 AM   #5
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Thanks for the info. I've tweaked things again and managed to get it a little better, my approach has been to get the upshift adjusted so I can at least shift up 1 at a time. I've checked that swing on the derailleur is smooth and grit free (I did this with the cable off) and the spring also feels OK.

I've checked the cables but personally I don't have a reference to say if they are running too tight. With the cable off the derailleur I've wiped it clean, slid it through as much as I can and unclipped the outers from the housings on the frame, after cleaning it I've also wiped a bit of teflon lube over the inner.

This might be why I've got a bit of a better shift, but I'm after pin point accuracy and certain shifts each and every time.
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Old 02-05-07, 07:34 AM   #6
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Quote:
Originally Posted by Al1943
Slow hesitant shifting, especially upshifting, is usually related to the condition of the shift cables and cable housings. You can test for this by loosening the short housing found at the rear derailleur, slide the housing forward up the cable exposing the cable for lubrication. Re-attach, adjust, if you get significant improvement you need new cables and expecially new cable housings.

As you upshift, cable is released from the shifter and pulled by the derailleur's spring tension. Any excess friction within the housings will slow or impede the shift.

Al
This is the "weak link" in STI shifters.
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Old 02-05-07, 09:22 AM   #7
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Also try hosing out the insides of the shifters with WD40 or similar solvent to loosen dried and dirty grease.

Al
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Old 02-05-07, 11:20 AM   #8
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Excuse me if this check is obvious - but I didn't see mention of it when you went through your laundry list of all the tweaks you've tried: With the rear derailleur in the smallest cog, pull out all the slack in the cable. I assume you did this since you said you lubed your cables, but you mentioned it doesn't upshift (into a larger rear cog) initially which makes me think you've got slop in your cables.

If the section of compressionless housing by the rear derailleur is SHORT, why not have a new peice cut and fitted that is longer with a more graceful curve to it. If you do this you will most likely need a new derailleur inner wire.
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