skipping chain

mrdoofer
mrdoofer Posts: 71
edited November 2008 in Workshop
My chain keeps skipping on my relatively new bike, it started to skip when I was in the small chainring going for it uphill. It now has developed to skipping all the time on both chainrings, and skips inconsistently when in most gears.

If I suspend the bike and shift through the gears it responds well, it seems to be skipping when under stress.

The derailleur is a shimano 105 as well as the cassette. Hoping I just need to give it a simple tweak so I can get out on it again tomorrow! any pointers would be great!

Comments

  • Mister W
    Mister W Posts: 791
    When you say "skipping" what do you actually mean? Is it jumping between cogs or just rattling a bit?
  • ACMadone
    ACMadone Posts: 300
    Sounds like it may well be cable tension. Can you take it back to your LBS and get them to give you a free service? Most places do after a month of purchase.
  • ACMadone
    ACMadone Posts: 300
    Sounds like it may well be cable tension. Can you take it back to your LBS and get them to give you a free service? Most places do after a month of purchase.
  • mrdoofer
    mrdoofer Posts: 71
    Thanks, To be more precise what is actually happening is that the chain shifts between the gears but seems to be sliding over the cogs.
  • Nuggs
    Nuggs Posts: 1,804
    mrdoofer wrote:
    Thanks, To be more precise what is actually happening is that the chain shifts between the gears but seems to be sliding over the cogs.
    Is it shifting up (to the smaller cogs) or down (to the larger cogs)?

    If it's shifting to the smaller cogs, turn the barrel adjuster on the right hand side of the downtube anticlockwise to increase cable tension.

    If it's shifting onto the larger cogs, turn the barrel adjuster clockwise.

    For fine-tuning cable tension, check out the guide on the Park Tool website.
  • mrdoofer
    mrdoofer Posts: 71
    I don't think its skipping up and down gear, more like it's sliding across the top of the selected gear, if that makes any sense.

    When I shift gear it changes smoothly, I could be going in the gear for a while without any noticeable noises, then when I'm pedaling it feels like the chain looses the teeth then finds them again. I doesn't jump up or down a gear. It can do this once and catch again, or slide catch, slide catch. Through the pedals it feels like the chain is finding the groove in the cog and then jumping out and trying again. It's definetly not grinding in between two gears.

    It was sliding forwards so often last night that I thought maybe the freehub could be knackered, Ive never had one go on me before so I don't know what that would be like.
  • Mister W
    Mister W Posts: 791
    It's impossible for the chain to "slide forwards" unless it's jumping off the cog. It's probably trying to jump to a different cog because your mech is out of alignment...... which could be due to the cable stretching. Try Nuggs suggestion of adjusting it using the adjusters on the cable or you may have one on the mech. DO NOT ADJUST THE LIMIT SCREWS!
  • mrdoofer
    mrdoofer Posts: 71
    ok I'll try adjusting the cable tension, and I'll leave the limit screws well alone!
  • Nuggs
    Nuggs Posts: 1,804
    Mister W wrote:
    It's impossible for the chain to "slide forwards" unless it's jumping off the cog.
    Yes it is - try using a new chain with a worn cassette!
  • mrdoofer
    mrdoofer Posts: 71
    I'm pretty sure it is "slipping" but can't figure out why this would occur with a new (sub 500 mile ridden) bike, I'll check the tension in the morning.

    Would be good to hear any other checks I could make as well as cable tension.

    Thanks.
  • John.T
    John.T Posts: 3,698
    Nuggs wrote:
    Mister W wrote:
    It's impossible for the chain to "slide forwards" unless it's jumping off the cog.
    Yes it is - try using a new chain with a worn cassette!
    It is then jumping off the cog as suggested. Unlikely on a new bike though. Most likely index adjustment or he has bent the mech hanger.
    My Fleet.

Categories