odd chain skipping of chainring problem

oddjob13
oddjob13 Posts: 3
edited April 2008 in MTB workshop & tech
Hi,

A brief outline of my problem.

I have an old mountain bike, which I decided to pull the triple chainring off of and replace it with a single, larger 48 tooth chainring. I attached it to the central ring mount of my crank and whilst I was playing with the drivetrain I decided to fit a new cassette and chain. I did as you should and measured the new chain round the chainring and largest cog, adding two links to the chain.

Fitted and fettled the gears and all seemed fine until I took the bike out for spin. The gears change fine most of the time but from time to time whilst changing gear the chain skips off the chainring. This also happens occaisionally when bouncing over uneven terrain when not changing gear.

Any suggestions as what can be causing this? Chain too long/short? position of the chainring? me being a moron? Any advice would be greatly welcomed.

Lastly, as I put a more road biased cassette on my bike, and as I'm running on a single ring would I benefit by going to a short cage deraillieur?

Comments

  • nicklouse
    nicklouse Posts: 50,675
    yep a short cage can be used.

    what gears do you mainly use?

    put the front mech back on and lock it in position over the ring so as to stop the chain jumping off as easily.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Shadowduck
    Shadowduck Posts: 845
    It does sound a lot like your deailleur isn't always taking up the slack in the chain properly for some reason. Is it in decent nick, moving smoothly etc? Does the chain come off on upshifts but not downshifts?
    Even if the voices aren't real, they have some very good ideas.
  • oddjob13
    oddjob13 Posts: 3
    I mainly use my taller gears as I'm on road more often than not. And the skipping happens most often when i'm shifting to an easier, larger cog.

    The deraillieur seems to be moving ok. That said it's as old as the bike itself which is about 11/12 years. Hence why I'm planing on replacing that as well.