Is the chain skipping or what?

Discussion in 'Mountain Bikes' started by Pat, May 3, 2003.

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  1. Pat

    Pat Guest

    Hello. I have a problem with my mountainbike that's been pretty common with bikes I've had but now
    find it really irritating and want to fix it.

    When I put a lot of pressure on the pedal (like when I start pedaling from rest), the pedal jerkily
    advances a little bit without the wheels moving and then it "catches" and the wheels turn as the
    pedal turns. It almost feels like every link on the chain is skipping one cog but that seems
    impossible for every cog would have to be worn.

    When it happens, it's a jolt to the body which once in a while almost knocks me off the bike.

    The bike is not knew so I think it's due to worn parts but I can't figure out what exact parts are
    causing it. Any help would be appreciated.

    Thanks.
     
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  2. Chris

    Chris Guest

    "Pat" <[email protected]> wrote in message news:[email protected]...
    > Hello. I have a problem with my mountainbike that's been pretty common
    with
    > bikes I've had but now find it really irritating and want to fix it.
    >
    > When I put a lot of pressure on the pedal (like when I start pedaling from rest), the pedal
    > jerkily advances a little bit without the wheels moving
    and
    > then it "catches" and the wheels turn as the pedal turns. It almost feels like every link on the
    > chain is skipping one cog but that seems impossible for every cog would have to be worn.
    >
    > When it happens, it's a jolt to the body which once in a while almost
    knocks
    > me off the bike.
    >
    > The bike is not knew so I think it's due to worn parts but I can't figure out what exact parts are
    > causing it. Any help would be appreciated.
    >
    > Thanks.
    >

    Check the cassette - the group of cogs on the rear wheel - for excess wear. If the spaces between
    teeth on the cassette are shallower than half-circles, you need a new one of them. Very, very
    careful adjustment of the rear derailleur can help to alleviate the skipping, but that is just
    prolonging the inevitable. If your chain is new and the cassette is not the skiping will be very
    noticable.

    FWIW, I get less than a thousand (mostly dirt) miles out of cassettes...do you know how much riding
    was done on yours?

    If you replace the cassette and chain, and double-check your rear mech setup, you should have
    no problems.

    Of course, you could just need new chainrings up front. Or both...

    Chris
     
  3. Dave Stocker

    Dave Stocker Guest

    Worn cogset will do it. You say "worn parts", which points in this direction. Does it skip all over
    the cogset? Or just on a favorite cogwheel(s)? If the bike gets a new chain and suddenly starts
    skipping, worn cogset is the magic ticket. One of my bikes always slips on the smallest two cogs and
    this started the last time I changed the chain. Now if only that shiny new cogset could make it from
    the bench to the bike...

    Note- you may not need to change the whole cogset. I tend to get much higher wear on the smaller
    wheels than the bigger ones. I presume because of higher contact forces between the chain and
    cogwheel. Take your cogset out and you may see that the outer two are separate (e.g. most Shimanos)
    or that even the whole set can be taken apart. My wallet says that it is always cheaper to replace
    one cogwheel than an entire set.

    Alternatively, it could be a maladjusted deraileur. I have this problem on a new (less than 100km)
    bike. I get skipping all over the cogset and it drives me bananas. I think it is going up on the
    stand before today's ride.

    -Dave
     
  4. Pat wrote:
    > Hello. I have a problem with my mountainbike that's been pretty common with bikes I've had but now
    > find it really irritating and want to fix it.
    >
    > When I put a lot of pressure on the pedal (like when I start pedaling from rest), the pedal
    > jerkily advances a little bit without the wheels moving and then it "catches" and the wheels turn
    > as the pedal turns. It almost feels like every link on the chain is skipping one cog but that
    > seems impossible for every cog would have to be worn.
    >
    > When it happens, it's a jolt to the body which once in a while almost knocks me off the bike.
    >
    > The bike is not knew so I think it's due to worn parts but I can't figure out what exact parts are
    > causing it. Any help would be appreciated.
    >
    > Thanks.

    the "delay" you're feeling is due to how the rear hub works. The skip you feel is the movement of
    the cassette and freehub until the mechanical conection to the main hub is made. Many better (read:
    more expensive) hubs have quicker "engagement", because they have more engagement points.

    If it only happens when you start pedalling (whether starting or coasting), then thats what it is.
    You know those clicks the rear hub makes? Thats the mechanical "pawls" clicking by the engagement
    points - they're what allow the hub to "freewheel", IE coast.

    for a general idea: http://www.bikepro.com/products/hubs/hubs_jpg/d1dd_ringle_pawl.jpg The silver
    parts are the pawls.

    You can prove this to yourself by carefully wheeling the bike backwards, then RIGHT after the hub
    clicks, stop, and put a little bit of pressure on the pedal. It won't move far at all before it
    engages. Then try it about as far from a click as you can - you'll feel the extra movement.

    Jon Bond
     
  5. Jonathan Bond wrote:
    > Pat wrote:
    >
    >> Hello. I have a problem with my mountainbike that's been pretty common with bikes I've had but
    >> now find it really irritating and want to fix it.
    >>
    >> When I put a lot of pressure on the pedal (like when I start pedaling from rest), the pedal
    >> jerkily advances a little bit without the wheels moving and then it "catches" and the wheels turn
    >> as the pedal turns. It almost feels like every link on the chain is skipping one cog but that
    >> seems impossible for every cog would have to be worn.
    >>
    >> When it happens, it's a jolt to the body which once in a while almost knocks me off the bike.
    >>
    >> The bike is not knew so I think it's due to worn parts but I can't figure out what exact parts
    >> are causing it. Any help would be appreciated.
    >>
    >> Thanks.
    >
    >
    >
    > the "delay" you're feeling is due to how the rear hub works. The skip you feel is the movement of
    > the cassette and freehub until the mechanical conection to the main hub is made. Many better
    > (read: more expensive) hubs have quicker "engagement", because they have more engagement points.
    >
    > If it only happens when you start pedalling (whether starting or coasting), then thats what it is.
    > You know those clicks the rear hub makes? Thats the mechanical "pawls" clicking by the engagement
    > points - they're what allow the hub to "freewheel", IE coast.
    >
    > for a general idea: http://www.bikepro.com/products/hubs/hubs_jpg/d1dd_ringle_pawl.jpg The silver
    > parts are the pawls.
    >
    > You can prove this to yourself by carefully wheeling the bike backwards, then RIGHT after the hub
    > clicks, stop, and put a little bit of pressure on the pedal. It won't move far at all before it
    > engages. Then try it about as far from a click as you can - you'll feel the extra movement.
    >
    > Jon Bond
    >

    Hmm, I read your post as "the bike is new, so it's not due to wear". My bad.

    Yeah, go by what the other guys say.

    Jon Bond shouldn't try to be helpful during finals period.
     
  6. David Kunz

    David Kunz Guest

    Pat wrote:
    > Hello. I have a problem with my mountainbike that's been pretty common with bikes I've had but now
    > find it really irritating and want to fix it.
    >
    > When I put a lot of pressure on the pedal (like when I start pedaling from rest), the pedal
    > jerkily advances a little bit without the wheels moving and then it "catches" and the wheels turn
    > as the pedal turns. It almost feels like every link on the chain is skipping one cog but that
    > seems impossible for every cog would have to be worn.
    >
    > When it happens, it's a jolt to the body which once in a while almost knocks me off the bike.
    >
    > The bike is not knew so I think it's due to worn parts but I can't figure out what exact parts are
    > causing it. Any help would be appreciated.
    >
    > Thanks.
    >

    Chain skip is the sign of a worn cog or a chain that's worn differently from the cogs and no longer
    engages all of the teeth properly (new chain, old cogs). This doesn't take long with improper chain
    maintenance or even with good chain maintenance in bad conditions (lots of water and grit/mud :)).

    It's probably a combination of the above.
    - Measure pin-pin on 12 links of the chain. If it's more than 12-1/16" to 12-1/8", you probably need
    a new chain (a new chain's 12" -- 1"/link). You may need to measure 6 links and 1/2 the above. If
    you replace the chain on a bike that's already skipping, you'll probably need to replace the
    chainrings and the cassette also. They'll be worn to the wider link spacing and skip with the new
    chain because only 1 tooth will bear the load!
    - Does it skip in any front chainring? If so, the probalem's probably the cassette. If only one
    chain ring skips, try replacing it.
    - Does it skip in any rear cassette gear? If it skips in only some of the cassette gears, it's
    probably a worn cassette. Otherwise, it's worn chainrings and you need to repeat the previous step
    :)). It'll usually skip in the gears that you use the most (like the one that you start out
    in :)). Replace the cassette.

    Note that replacing one of the above may not fix the problem. It may just show you the next worn
    part that needs replacing...

    David
     
  7. Mx-Pilot

    Mx-Pilot Guest

    i had this only when i broke my chain and bought a new one.

    "Jonathan Bond" <[email protected]> wrote in message
    news:[email protected]...
    >
    >
    > Jonathan Bond wrote:
    > > Pat wrote:
    > >
    > >> Hello. I have a problem with my mountainbike that's been pretty common with bikes I've had but
    > >> now find it really irritating and want to fix it.
    > >>
    > >> When I put a lot of pressure on the pedal (like when I start pedaling from rest), the pedal
    > >> jerkily advances a little bit without the wheels moving and then it "catches" and the wheels
    > >> turn as the pedal turns. It almost feels like every link on the chain is skipping one cog but
    > >> that seems impossible for every cog would have to be worn.
    > >>
    > >> When it happens, it's a jolt to the body which once in a while almost knocks me off the bike.
    > >>
    > >> The bike is not knew so I think it's due to worn parts but I can't
    figure
    > >> out what exact parts are causing it. Any help would be appreciated.
    > >>
    > >> Thanks.
    > >
    > >
    > >
    > > the "delay" you're feeling is due to how the rear hub works. The skip you feel is the movement
    > > of the cassette and freehub until the mechanical conection to the main hub is made. Many better
    > > (read: more expensive) hubs have quicker "engagement", because they have more engagement points.
    > >
    > > If it only happens when you start pedalling (whether starting or coasting), then thats what it
    > > is. You know those clicks the rear hub makes? Thats the mechanical "pawls" clicking by the
    > > engagement points - they're what allow the hub to "freewheel", IE coast.
    > >
    > > for a general idea: http://www.bikepro.com/products/hubs/hubs_jpg/d1dd_ringle_pawl.jpg The
    > > silver parts are the pawls.
    > >
    > > You can prove this to yourself by carefully wheeling the bike backwards, then RIGHT after the
    > > hub clicks, stop, and put a little bit of pressure on the pedal. It won't move far at all before
    > > it engages. Then try it about as far from a click as you can - you'll feel the extra movement.
    > >
    > > Jon Bond
    > >
    >
    > Hmm, I read your post as "the bike is new, so it's not due to wear". My bad.
    >
    > Yeah, go by what the other guys say.
    >
    > Jon Bond shouldn't try to be helpful during finals period.
     
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