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rear derailleur- puzzled

carrockcarrock Posts: 1,103
edited July 2010 in Workshop
had some shifting problems which a quick twiddle of the cable tension didnt solve, so one service laterall was well- initially

Problem returned

Basically, the bike hangs on to gears when changing, both up and down

More cable tension makes the changing down perfect, but then there's not enough slack in the cable to change up on to the smaller sprockets. Slackening off the cable sorts it, but then it won't shift back down onto the larger sprockets. and so on

I left the bike on the lowest cog, and changed up with the shifter so as to slacken the cable, remove it from the guides and lube it- there doesnt seem to be any stickiness in the cables at the frame end

So I'm stumped- the only thing I can think of is the derailleur hanger is bent, but it doesnt look obviously bent, although I don't have a gauge to check it with

It has had a new chain, recently, and i swapped my wife's back wheel ( identical ) with mine to see if it was the cassette but that made no difference

So I'm stumped......cleaned all lubed all parts- removed the rear wheel and the deraiileur moves freely by hand, loads of spring tension, etc.

:?

Posts

  • nicklousenicklouse Posts: 81,520 Lives Here
    get the hanger checked.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • carrockcarrock Posts: 1,103
    I was thinking that- I put the bike in the car a lot, and sometimes my wife's bike sits on top of it- lying flat obviously- both bike's weight total about 16-17kg, so I guess even half of that weight might bend the hanger

    By eye is not enough- I assume I'll need a park tool special guage, or an LBS

    It does seem as though the range of each shift is not quite large enough- which would be the case as a bent hanger would reduce the effective travel

    Thanks
  • nicklousenicklouse Posts: 81,520 Lives Here
    it does funny things depending on which way it has bent.

    but it sounds like you have checked everything else so.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • rakerake Posts: 3,204
    the only two thing left i can think of are the tension adjuster and the cable being clamped wrong.
  • carrockcarrock Posts: 1,103
    think what i'll do is line the 2 bikes up next to each other and see if my wife's hanger is at the same angle as mine ( same wheels, same groupset )

    But I'm running out of ideas if it's not the hanger- the only cable tension adjuster is the one next to the rear dropout I assume
  • rakerake Posts: 3,204
    i meant the tension screw near the mech bolt. i dont know what it's called it alters the distance from the top pulley to the sprockets.
  • nicklousenicklouse Posts: 81,520 Lives Here
    rake
    the B tension screw.

    if that is wrong IE top jockey wheel to close you hear/feel a BBBBRRRR as cog and wheel rub. if the gap is too big it does not make too much difference.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • paul64paul64 Posts: 278
    Is the inner cable sticking in the outer cable, perhaps that needs lubricating?
  • neebneeb Posts: 4,430
    the cable being clamped wrong.
    Do check this. I once setup a new campag rear derailleur and routed the cable just very slightly wrongly through the clamp bolt, and had exactly the problems you describe.
  • jermasjermas Posts: 484
    edited July 2010
    Sounds like you need some new cables. If its 10 speed just a slight bit of drag in the cables is enough to produce what you describe. Lubricating the cables can work initially, but the problem soon returns.
  • Stuy-bStuy-b Posts: 248
    for the sake of £15 or so replace the cable (inner and outer) with a good Teflon coated cable. gotta be worth a try? and if it doesn't work then when you do sort it you'll have new cables anyway.
  • holybinchholybinch Posts: 417
    neeb wrote:
    the cable being clamped wrong.
    Do check this. I once setup a new campag rear derailleur and routed the cable just very slightly wrongly through the clamp bolt, and had exactly the problems you describe.

    Ditto
    FCN 4(?) (Commuter - Genesis Croix de Fer)
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  • carrockcarrock Posts: 1,103
    checked the hanger this morning it's fine

    Bike is 1 year old still under warranty and just been serviced, so it's going back to LBS tomorrow
    I unhooked the cable outer and it slides smoothly along the cable itself- just wondering if it's the deraiiluer as it hardly seems to move between some of the gears

    There does seem to be a bit of resistance at the lever so perhaps the cable at the bar end is sticking
  • deswellerdesweller Posts: 5,175
    Have a look inside the shifter. Sometimes the cables detach from the pip at the end, fray where they follow the pulley radius in the shifter and jam the shifter up.
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  • carrockcarrock Posts: 1,103
    its going back to shop tomorrow as it's still under warranty. Dirty mech or cables etc I was happy to fix myself as it's wear and tear, but I hink the problem is either the derailleur or the shifter

    I detached the cable and blasted through the cable outer with spray lube and it's fine

    Noticed that on some shifts the deraiileur hardly moves, so not surprising it's not changing cogs smoothly

    Only last week it was in for a service as the freewheel had gone very noisy, so has had new freewheel and chain
  • carrockcarrock Posts: 1,103
    it went to the LBS today and they replaced the lower cable outer next to the derailleur and all was well

    I'd stripped the cable outer and sprayed it with solvent on the inside, but once the plastic inner sheath is worn, it's time to change the outer

    LBS advises it's very common, and once a tiny bit of drag is there from a worn cable, it's enough to knock a 10 speed derailleur out of whack

    I'll know for next time

    Thanks to all who offered advice
  • Ben6899Ben6899 Posts: 8,898
    Glad you got it sorted mate. Happy spinning!
    Ben

    Bikes: Donhou DSS4 Custom | Condor Italia RC | Gios Megalite | Dolan Preffisio | Giant Bowery '76
    Instagram: https://www.instagram.com/ben_h_ppcc/
    Flickr: https://www.flickr.com/photos/[email protected]/
  • carrockcarrock Posts: 1,103
    Ben6899 wrote:
    Glad you got it sorted mate. Happy spinning!

    Thanks

    Only thing is the rest of the cables are grey- but they didnt have any grey cable so used black- and I just know it's going to annoy me so will probably buy a yard of grey gear cable and replace it again

    The wife thinks I'm pedantic.... :shock:
  • Ben6899Ben6899 Posts: 8,898
    carrock wrote:
    Ben6899 wrote:
    Glad you got it sorted mate. Happy spinning!

    Thanks

    Only thing is the rest of the cables are grey- but they didnt have any grey cable so used black- and I just know it's going to annoy me so will probably buy a yard of grey gear cable and replace it again

    The wife thinks I'm pedantic.... :shock:

    She's right! :wink:
    Ben

    Bikes: Donhou DSS4 Custom | Condor Italia RC | Gios Megalite | Dolan Preffisio | Giant Bowery '76
    Instagram: https://www.instagram.com/ben_h_ppcc/
    Flickr: https://www.flickr.com/photos/[email protected]/
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