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Chain Keeps Slipping On Certain Gears

mikeyj28mikeyj28 Posts: 754
edited May 2010 in MTB workshop & tech
Hi all

Bit of a seriously annoying problem. My chain sometimes slips when i am in the middle front chainring and either the 3/4/5th largest chainrings at the rear.
It mostly happes when i am trying to pedal kinda hard up a hill.
It doesn't do it every time without fail but it is fairly regular and sometimes i have half fallen off hitting my handlebars with my stomach before regaining control when the chain seems to go.

Overall it is annoying as it ruins part of your ride as you are worried of it happening.
What is wrong? I am censored with working the rear mech or do i need a new chain and/or cassette?? My cassette is 6 years old and has clocked up a good few miles. Maybe its worn? Or do i need to fiddle with those H and L screws on the rear mech?

Your advice is much appreciated.

Thanks
Constantly trying to upgrade my parts.It is a long road ahead as things are so expensive for little gain. n+1 is always the principle in my mind.

Posts

  • peter413peter413 Posts: 5,120
    Try fiddeling with the rear mech.

    Have you replaced the chain but not the cassette. You should usually replace both at the same time unless the chain is less than .75% worn and even then you may still need to replace both
  • mikeyj28mikeyj28 Posts: 754
    peter413 wrote:
    Try fiddeling with the rear mech.

    Have you replaced the chain but not the cassette. You should usually replace both at the same time

    Hi Peter

    Thanks for the reply. I last replaced the chain 3 years ago (yes ages i know) but have not replced the cassette.
    If i fiddle with the rear mech what screws should i turn and roughly do i need a slight adjustment of the screws or a greater turn of the screws.?
    Constantly trying to upgrade my parts.It is a long road ahead as things are so expensive for little gain. n+1 is always the principle in my mind.
  • peter413peter413 Posts: 5,120
    You shouldn't need to touch the limit screws unles the cables have stretched.

    There should be a barrel you can twist on the back/left of the mech (the cable enters through it), fiddle with that for a bit, works for me.

    Just stick the bike in a stand or get someone to hold the rear wheel in the air, shift into first gear on the middle ring and shift down one gear at a time, fiddling with the barrel adjuster until it goes up and down the whole block smoothly.

    After that long it may be time to think about a new chain, cassette and chainrings
  • mikeyj28mikeyj28 Posts: 754
    peter413 wrote:
    There should be a barrel you can twist on the back/left of the mech (the cable enters through it), fiddle with that for a bit, works for me.

    After that long it may be time to think about a new chain, cassette and chainrings

    GGrrrr the expense of new chainrings ,cassette and chain. Why am i so tight (more like why desire top end stuff!!)

    Thanks for your help. Will have a fiddle with the barrell adjuster and see how i get on.

    Thanks again
    Constantly trying to upgrade my parts.It is a long road ahead as things are so expensive for little gain. n+1 is always the principle in my mind.
  • alfabluealfablue Posts: 8,497
    you shouldn't touch the limit screws at all, regardless of cable stretch, and they have no effect on the chain other than stopping it over shifting beyond the smallest or largest sprocket.
  • peter413peter413 Posts: 5,120
    alfablue wrote:
    you shouldn't touch the limit screws at all, regardless of cable stretch, and they have no effect on the chain other than stopping it over shifting beyond the smallest or largest sprocket.

    And if the cables have stretched, this can change. Otherwise, why have a cable at all :wink:
  • ride_wheneverride_whenever Posts: 13,279
    if you're censored with this, ask your lbs nicely to teach you in exchange for shiney beer tokens or something, you'll have to pay for them to do it, but if you play your cards right then you'll know properly how to do it.
  • Chunkers1980Chunkers1980 Posts: 8,035
    peter413 wrote:
    alfablue wrote:
    you shouldn't touch the limit screws at all, regardless of cable stretch, and they have no effect on the chain other than stopping it over shifting beyond the smallest or largest sprocket.

    And if the cables have stretched, this can change. Otherwise, why have a cable at all :wink:

    Mate - limit screws have NOTHING to do with cable stretch. Cable stretch is sorted by the barrel adjuster(s) or pulling more cable through the mech. Limit screws only need to change if the relative position of the mech and/or cassette changes.
  • kaytronikakaytronika Posts: 580
    peter413 wrote:
    alfablue wrote:
    you shouldn't touch the limit screws at all, regardless of cable stretch, and they have no effect on the chain other than stopping it over shifting beyond the smallest or largest sprocket.

    And if the cables have stretched, this can change. Otherwise, why have a cable at all :wink:

    Mate - limit screws have NOTHING to do with cable stretch. Cable stretch is sorted by the barrel adjuster(s) or pulling more cable through the mech. Limit screws only need to change if the relative position of the mech and/or cassette changes.

    This.
    If your rear mech travels through the entire casette, don't adjust the limit screws.
    I found out the hard way when I was a nipper... Adjusted the screw so much that I pulled the rear mech in to the back wheel when I was pedalling down a road in front of two girls. :lol:

    Inch long, half inch wide scar on my knee to this day.
    --
    '09 Carrera Fury
    '94 GT Timberline FS
    '89 Saracen Tufftrax
  • CycloRosCycloRos Posts: 579
    If the drive train is years old and been used heavily then its time to replace the bits.

    By the sounds of it no amount of adjustments to the existing setup will make a damn bit of difference, slipping under load undoubtedly means worn parts...

    You can replace all the bits yourself (with the right tools) for less than £100 quid.
    Current Rides -
    Charge Cooker, Ragley mmmBop, Haro Mary SS 29er
    Pics!
  • ExeterSimonExeterSimon Posts: 830
    As in the other chain slipping thread lurking near this one, I'm going to mention chain measuring tools.

    Cheap..and can save you loads.
    Whyte 905 (2009)
    Trek 1.5 (2009)
    Specialized Stumpjumper FSR Comp (2007)
  • peter413peter413 Posts: 5,120
    Whoops, yeah, I keep thinking the bolt for the cable is a limit screw or sumin :roll:

    My mistake, I knew in my mind what I was on about, just didn't say it correctly
  • The RookieThe Rookie Posts: 27,804
    Seconded....

    As is the commenst about limits screws, cable stretch has NO EEFCT AT ALL on limit screws setting - what a ridiculous comment to make, clearly someone who has no idea about setting up a rear mech!

    Simon
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • mikeyj28mikeyj28 Posts: 754
    CycloRos wrote:
    If the drive train is years old and been used heavily then its time to replace the bits.

    By the sounds of it no amount of adjustments to the existing setup will make a damn bit of difference, slipping under load undoubtedly means worn parts...

    You can replace all the bits yourself (with the right tools) for less than £100 quid.

    Yes it looks like i am going to have to replace the drive train! Just really annoying as to get a light & decent drive train set up will cost me money.

    Thanks for the response guys
    Constantly trying to upgrade my parts.It is a long road ahead as things are so expensive for little gain. n+1 is always the principle in my mind.
  • peter413peter413 Posts: 5,120
    Seconded....

    As is the commenst about limits screws, cable stretch has NO EEFCT AT ALL on limit screws setting - what a ridiculous comment to make, clearly someone who has no idea about setting up a rear mech!

    Simon

    Actually I do, was just a simple mistake getting bolts/screws mixed up.

    Jeeez
  • The RookieThe Rookie Posts: 27,804
    Check each component in turn, FAQ's pr the partktools and Sheldonbrown sites....

    I had a rear shifting issue was driving me nuts, then I spotted a chain link starting to come apart, side plate was sticking out and catching the lower gear.....

    On my Daughters bie the skipping was clearly the gear teethm, the wear was obvious, replaced, no need to replace chain, all sorted.....

    Simon
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • peter413peter413 Posts: 5,120
    70 quid for a new drivetrain for me...

    SRAM PC951 chain - 13 quid
    SRAM PG970 cassette - 20 quid
    Shimano Deore Rings - about 30-40 quid, depending if you run a triple or double
  • The RookieThe Rookie Posts: 27,804
    peter413 wrote:
    Actually I do, was just a simple mistake getting bolts/screws mixed up.

    Jeeez

    PMSL.....you'll note my comment was posted at the same time as your correction, I couldn't have seen......

    Simon
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
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