Weird Gear Problem

[pfm401]

I'm hoping someone can help me with a "weird" gear issue. I have a Shimano Tiagra system with a triple up front and 10 at the rear.

My gears are set up but I can't get them quite right (and neither could the guy at the LBS). Changing down is no problem, pretty smooth down to the smallest cog. Then when you try to change up 1 (to 9th at the lever). it doesn't. Changing to 8th at the lever switches to 9 at the cog, 7th level 8 cog and so on, to 3rd at lever 4th at cog. The next up shift changes to 2nd at lever 2nd at cog i.e. correct!

Tweaking the index adjuster doesn't work, it stops the change down. In short, I can't win.

I looked at the change down / change up at the smallest cog. On the change down the rear mech moves (as expected) and changes. Changing up at the lever it hardly moves at all, so no surprise it doesn't shift at the cog. I can push it with my fingers, then it moves to 9th cog and stays there. So I was thinking it could be the cable tension, but see comment about adjuster above - seems to rule that out.

I should say that I crashed the bike on ice back in Feb, and the whole rear part of the drivetrain had to be replaced. LBS had to straighten the dropout as well, but it seemed OK. The cables etc are all fairly new (<1000 miles).

Any thoughts? My best guess is some sort of damage to the lever, I've had this before on a MTB shifter where the nipple housing was damaged and the change up then pulled the nipple into the damaged housing. I don't fancy messing with STIs though.

Thanks, Paul.

 

[steve50]

have you removed the cable and checked for movement / stiffness between the inner and outer cable sleeve?
Can you try another cable to eliminate the possibility of the cable being at fault, lift the rubber hood that covers the sti and do a visible inspection of the lever movement to see if there is anything obvious.

 

[mickle]

Was the mech replaced after the crash?

 

[midliferider]

In these situations I find that best is to start from the beginning. I mean replace the cable and start from scratch.
Before you guide the cable, you need to see whether the rear mech is working properly by shifting gears by pressing on the derailleur. You can adjust the limit screws at the same time.
Then guide the cable and adjust tensions.
That is what I learned at my maintenance course.
Where do you live? Happy to help if you are local.

 

[raleighnut]

Sounds like a sticky cable to me and the normal culprit is the short piece of outer from the mech to the frame stop.

 

[Rohloff_Brompton_Rider]

Sounds like a sticky cable to me and the normal culprit is the short piece of outer from the mech to the frame stop.

Sounds like that to me too. Plus check the length of the outer against other bikes, I had a similar issue and realised the outer was too long. Also check the outer is seated right at the Brifter end, again I had this issue when a Ferrell wasn't seated right.

 

[boydj]

Note : - a Ferrell is an overrated American actor in comedy films and probably too heavy to be useful in cycling, while a ferrule is an end cap for cables.

 

[Rohloff_Brompton_Rider]

Note : - a Ferrell is an overrated American actor in comedy films and probably too heavy to be useful in cycling, while a ferrule is an end cap for cables.

iPhone autocorrect is obviously a Hollywood buff.

 

[pfm401]

I'll try the cable again. The rear mech was replaced after the crash as it was taken out completely; bent gear hanger then caused it to pull up into the wheel etc. The mechanic replaced all my outers and the inner at the time as he was trying to sort out the gear change problem (by bending my frame back into shape at the dropouts so I hope he'd checked the cable first!).

I don't think it was 100% perfect after the LBS fixed it but will try again to make sure. It might take me a while to report back as it's rideable (just not perfect) and I'm making the most of the summer!

Cheers for the help.

 

[Karlt]

Is the cable routed correctly?

 

[mrandmrspoves]

I would replace the cable and outers (because it is cheap and easy to do) If that doesn't resolve the issue I would suspect derailleur hanger alignment. Easy to do with a £30 tool or try a different LBS.