Gears slipping help required.

Gregore
Gregore Posts: 17
edited May 2008 in Road beginners
I've had my road bike for approx 3 months with no problems what so ever, then whilst riding to work this morning every so often the chain seems to slip and there is no resistence on the pedals for a revolution then it returns to normal.
This was happening at different times in different gears and was very annoying as you can imagine.

Has anyone got any ideas as i need to ride home tonight.

thanks

Comments

  • schilbach
    schilbach Posts: 101
    Same for me!

    I know it's caused by the cables bedding in and stretching a bit - and I know there's adjustment screws on the deraileurs - I just don't know which way to turn them!

    Any advice appreciated!
  • CrookedCucumber
    CrookedCucumber Posts: 324
    schilbach wrote:
    Same for me!
    I know it's caused by the cables bedding in and stretching a bit - and I know there's adjustment screws on the deraileurs - I just don't know which way to turn them!

    There should be a cable tension adjuster on or near the cable, either at the shifter end or (more likely, these days, I think) on the derailleur housing itself. There will also be limit adjustments, usually marked `H' and `L', but in my experience they should not need adjusting after only a couple of months.

    As for which way to turn the cable tension adjustment, I've found that if I turn it a little way in one direction, and it doesn't get any better, it usually helps to turn it a little the other way :)

    I generally just put the bike on a stand (or upside down will do at a pinch), put the derailleur I'm not adjusting onto the middle position, then step up and down through the gears on the adjusting derailleur, tweaking the tension a little a bit until all the gears engage smoothly, and there is little or no rattle in any gear. If I do that, I usually find that the chain won't slip or change gear accidentally any more.

    There is a `standard' procedure for adjusting derailleur cable tension, which I'm sure is on this site somewhere, if you don't like my ad-hoc approach ;)
  • schilbach
    schilbach Posts: 101
    Brilliant Thanks CC!

    Those will be the the screw heads I can see on my Shiman Ultegra Hoods when I pull the brake levers??
  • Gregore
    Gregore Posts: 17
    Ill try that now thanks very much.
  • Rouge Penguin
    Rouge Penguin Posts: 347
    I think i'll jump on Gregore's post.

    Mine is doing something similar, but its when an amount of torque is put through the pedals. I've never had an issue with Small-small before, maybe as when you're young you can't put enough strain on it, but now if i've left it in S-S it slips when trying to pull away it just keeps on slipping.

    Very occasionally, its done it in Large-Small, but its once in a blue moon. 2 services at the LBS haven't solved it, mainly as i think they presume its a shifting issue. It feels like cassette is slipping on the hub.

    Any ideas? I think theres a new bike on the horizon, but would prefer not to throw the bike in the river in a fit of rage just yet.
  • Bronzie
    Bronzie Posts: 4,927
    schilbach wrote:
    Those will be the the screw heads I can see on my Shiman Ultegra Hoods when I pull the brake levers??
    NO!! On the rear mech - the thing that hangs down at the back wheel with the chain running through it!
    It's a Lifestyle! -+-+- Coggan Training Levels
  • nferrar
    nferrar Posts: 2,511
    @Rogue: Still could just be a cable-indexing adjustment needed (although an LBS should have sorted that). This most often shows up on extreme gearing like small-small (which you shouldn't really use anyhow), if it's only slightly out the chain will catch and ride up on the teeth then i guess jump a bit when it beds back down so it feels like suddenly something snaps and your pedal leg jumps forward. A mate had this on his MTB the other day and on a workstand it seemed indexed perfectly but it happened a lot out on the trails, looking at the bike from behind I could see the mech wasn't perfectly aligned with the sprocket it was in so adjusted the tension and the skipping hasn't happened since.

    The other thing it could be is a stiff link in the chain (just turn the pedals backward slowly and watch the chain links go through the jockey wheels and over the sprockets and make sure they all go around smoothly, if they don't flex the chainside to side at the stiff link with your thumbs to loosen it up.

    Finally if the chain jumps between different gears or takes a long time to shift this can be due to bad indexing but also dirt in the gear cable housing (usually the last section befor the rear mech) causing the cable to stick slightly.

    Anyone new to bike servicing should buy the Park Bike Repair Book or at least go here: http://www.parktool.com/repair/byregion.asp
  • PhilofCas
    PhilofCas Posts: 1,153
    having read the first post, it doesn't sound like chain/gears to me, I suspect it's the freewheel mechanism that has gone faulty
  • redddraggon
    redddraggon Posts: 10,862
    nferrar wrote:
    Anyone new to bike servicing should buy the Park Bike Repair Book or at least go here: http://www.parktool.com/repair/byregion.asp

    Or the even better "Zinn and the Art of Road Bike Maintenance"
    I like bikes...

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  • Rouge Penguin
    Rouge Penguin Posts: 347
    @NFERRAR
    Thanks a bunch for the advice, you decribe the problem exactly. Will go get my fingers dirty tonight.

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