Chain slipping off 28t cog and hitting spokes

high tower
high tower Posts: 47
edited March 2013 in Road beginners
Hi all, gears had messed up yesterday so spent some time this morning Before my ride getting them spot on or so I thought.
Changes up and down are slick. Adjusted front mech all working fine and smooth. Quite pleased with myself for a newbie.

Anyway the only problem I have is a tendancy for the chain to jump of the 28t it happens every so often but not every time. This happens if I am in the 34 or 50 front chain ring. I think it's just the h or l screw that needs adjusted but they are not marked on the rear mech and after this mornings carry on I thought I would ask here rather than starting something I might not be able to finish.

Hopefully just a slight turn of a screw and I may have cracked it, it's a tiagra group set by the way.


  • team47b
    team47b Posts: 6,425
    It's probably best if you read and follow this excellent guide, that way you will set it up perfectly and learn into the bargain. Straightforward enough. ... derailleur
    my isetta is a 300cc bike
  • ugo.santalucia
    ugo.santalucia Posts: 28,237
    Sounds like you need to tighten a bit the limit screw... clockwise on the left/top one depending on derailleur model. half a turn might be enough
    left the forum March 2023
  • desweller
    desweller Posts: 5,175
    If you pop the bike upside down and take a look in the derailleur you'll be able to see how the limit screws act on the mechanism.
    - - - - - - - - - -
    On Strava.{/url}
  • team47b
    team47b Posts: 6,425
    always worries me, :roll: people playing with limit screws, but...

    L is for low gear limit adjustment
    H is for high gear limit adjustment
    my isetta is a 300cc bike
  • All sorted. Thanks all. Very slight adjustment and all fine. Followed the link once it was all working just to make sure. Very easy if you take it step by step and have bit of patience.

    What a difference having confidence in your gear changes, nice and quiet and smooth with no chain falling off. In fact it was so good I managed my first 50 mile ride today at an average of 14.1 mph. Not bad for an Asthmatic 40 year old who only took up cycling in October.