Chain slipping

hairlinefracture
hairlinefracture Posts: 7
edited July 2007 in MTB workshop & tech
Hi,

I have recently bought a specialized HRXC. It is my first mountain bike in years and this is the first time I have taken riding seriously. I got the bike that I could afford and really enjoy riding it.

I want to look after this bike, regularly maintain it etc. i ride it every day no matter what the weather as it is my only means of transport. In the last 2 weeks I have noticed when i have the chain on the lowest (toughest) gear, which is most of the time, the chain has started to slip. It feels like the teeth on crank aren't holding the chain properly. I don't know anything about bikes yet so I may not be describing this very well. However, it is a nuisance and very frustrating.

Can you tell me what could be causing this to happen?
Do I need to put more lube on the chain?

Thanks

Comments

  • nicklouse
    nicklouse Posts: 50,673
    check that there is no muck between the smallest cog and the next.

    could be worn out.

    if new take it back for its first service.

    read park tools rehow to do things.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • hairlinefracture
    hairlinefracture Posts: 7
    ok cheers,

    I actually just got it back from its first service and although they improved the gear shifts, the slipping has started happening.

    If it isn't muck, could it actually been worn out in the space of 6 weeks of riding?
  • nicklouse
    nicklouse Posts: 50,673
    if it has just come back. go back and ask them what is going on.

    yes it could be worn out.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • hairlinefracture
    hairlinefracture Posts: 7
    ok. will do.

    Thanks
  • MentalRaver
    MentalRaver Posts: 221
    nicklouse wrote:
    check that there is no muck between the smallest cog and the next.

    this exact thing fouled my gears. Cleaned it out today and never felt better and smoother!


    I reckon it was still Les Gets mud too!!!!!!!!!!!!
    Too enthusiastic about biking for my friends...want to ride somewhere in the SE? TELL ME!!! hamsterscanswim@hotmail.com - and yes they can!
  • stu8975
    stu8975 Posts: 1,334
    Ask your LBS to check it for stretching, also have a closer look at the cassette and chainset teeth for damage or excessive wear. Does it slip in only certain gears?
    ANTHEM X
    Youth
  • hairlinefracture
    hairlinefracture Posts: 7
    yeah, it only slips on the toughest gear.
  • nicklouse
    nicklouse Posts: 50,673
    ok an other thing to get the LBS to chech ot that the lock ring is compatable with the smallest cog. it has been none for ones that are too big to be fitted and work for a while but then the chain starts junping. rare but has been known to happen.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • mc
    mc Posts: 70
    Could be the rear mech limit screw just needing tweaked slightly.

    Easiest way to check, is flip the bike over and stand it on it's bars/seat. Now spin the pedals slowly and move to the problem gear (big ring front aswell)
    Now stand back and look to see if the chain/top jockey wheel is sitting central on the small sprocket (move up to the next sprocket and compare alignment if you're not sure). If it's not sitting central, adjust the relevant stop screw (think it's the L one - as you turn it, you should see the mech move. If it doesn't move, try the other screw). Adjust it till everything looks inline, and try the bike.
    If everything looks inline, try adjusting the limit screw quarter of a turn in each direction to see if it improves things, or makes them worse.
  • MarvintheAndroid
    MarvintheAndroid Posts: 409
    Sounds like it's jumping (ghosting), not slipping - that is, it isn't in gear properly. I agree with MC, try loosening the limit screw half a turn.

    Marv.
    What tree ? ...........

    Trek 8000 ZR XC hardtail.
  • stu8975
    stu8975 Posts: 1,334
    If you turn your bike upside down and put it in the same gearing as your problem area, does it shift ok or does it take a few seconds before it changes? if poss can you take a couple of closeup pics of you rear mech/cassette when its in the hardest gear and of your smallest cog on the cassette (we can get a better idea if its lined up as it should and that the cog isnt damaged or badly worn).
    ANTHEM X
    Youth
  • hairlinefracture
    hairlinefracture Posts: 7
    I checked the receipt that I was given after the service. It states that the rea\e mech and hager are damaged. I will go see them today and see what exactly is damaged. This may be the problem but it is only happening on the toughest gear and i would expect the problem to be on all gears if there was any major damage.
  • The BIG GT
    The BIG GT Posts: 655
    It could also be a stiff link in the chain. This often only becomes apparent on the smallest rear cog as the chain has to curve into a tighter loop and this may be beyond the point the link will move, so it 'slips'.

    This will be less likely to have an effect on larger cogs as the chain does not have to move as much as it is straighter.

    The best way to quickly check is to slowly backpedal while studying the chain as it passes the cog and the rear mech jockey wheels (the other obviously affected area).

    Hope that this helps.
    Now living happily at http://www.uk-mtb.com !!
  • hairlinefracture
    hairlinefracture Posts: 7
    Thank you for all the comments.

    I took into my LBS this afternoon and the rear mech and hanger are twisted. I have no idea how this happened but at least I know what's wrong. I've ordered a new rear mech and at the same time it is an upgrade so hopefully it is a little more robost.

    Thanks again.

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