Rear mech won't change gear

hostman
hostman Posts: 104
edited March 2014 in Workshop
Hi,

While on a ride this morning, my rear mech decided to stop shifting, it's shimano 105 all round. This was quite amusing, given I still had 5 miles or so to get home. So my gear choices were hard on small front ring, or hard on big front ring.

A mile or so before this, I noticed it wouldn't change up to the biggest sprocket. I'm fairly sure I heard a click at the point it stopped shifting altogether and not just the usual click when shifting up / down.

I changed the chain yesterday for a new one, this is probably just a coincidence. The drivetrain was considerably smoother with the new chain.

So where should I start to diagnose this?

Comments

  • neilo23
    neilo23 Posts: 783
    Does the derailleur move in and out if you use your hand instead of the lever?
  • mattv
    mattv Posts: 992
    I guess cable snapping and frayed up in the lever.
  • Welsh boy
    Welsh boy Posts: 38
    My friend had a similar problem, it was the shifter which had packed in, cost him a new rear shifter.
  • chris_bass
    chris_bass Posts: 4,913
    Sounds like the cable snapped if you were only left with small on the casette. Did you feel or hear anything when it stopped?
    www.conjunctivitis.com - a site for sore eyes
  • hostman
    hostman Posts: 104
    neilo23 wrote:
    Does the derailleur move in and out if you use your hand instead of the lever?

    It can physically move when I push it.

    As others have suggested, it could be the cable connection within the shifter on the bars. Be it the cable itself or another mechanism attached to it.

    I'll try and take the thing apart tonight, failing that I'll take it to a bike shop for repair.
  • dgunthor
    dgunthor Posts: 644
    probably the nipple on the end of the cable has broken off - seen this a few times.
  • hostman
    hostman Posts: 104
    So I guess this is why it won't shift :)

    m5x7BSK.jpg

    I've come this far taking the cable out, may as well put a new cable back. Where's my card, I need some tools ...
  • mattv
    mattv Posts: 992
    You are lucky you were still able to get it out. Sometimes they fray up so bad you can't get the bits out.
  • hostman
    hostman Posts: 104
    hmmm, had a closer look last night after pulling the cable out, there is indeed frayed cable stuck in the shifter.

    How much of the shifter can you usually take apart to access the internals?
  • mattv
    mattv Posts: 992
    You can remove the whole lever assembly mechanism. Any more than that is difficult. Try some tiny tweezers, if you can't get the bits out it's £100 fir a new lever assembly....
  • hostman
    hostman Posts: 104
    Everything arrived today that I need to change cable. Tackling it now, stopped to share this photo!

    wdN9lXv.jpg
  • mattv
    mattv Posts: 992
    You should be able to get that out easy enough as long as the strands haven't come off and worked into the mechanism.

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