Rear mech cable issues

Ult
Ult Posts: 60
edited April 2014 in MTB workshop & tech
Hi,
I have a Trek Superfly 100. The rear mech cable is becoming so contaminated after 1-2 rides that I can no longer shift at all (or at best have to use the palm of my hand). Some of the cable does not have an outer as per original supply but have tried with and without an outer. The cables both inner and outer are always decent quality and have also tried it with a wider outer, grease to try to waterproof slightly and have now run out of ideas.
You can see/feel that the last 3rd of the cable (from BB to mech) is filthy and gritty after one ride.
Any ideas would be welcomed.

Thanks

Comments

  • jimothy78
    jimothy78 Posts: 1,407
    Although cables are prime suspect, if it's getting sticky that quickly after new ones are fitted then it might not necessarily be the cables - sometimes the parallelogram pivots get choked with dirt. Check how freely the mech moves independent of the cable - if there's any gritty feeling or resisitance when moving it by hand, then this will be exagerated through the cable and shifter operation. If this seems likely, take the mech off the bike and thoroughly clean and lube all the pivots.
  • Ult
    Ult Posts: 60
    Thank You. I will try that. It is smooth as silk with new cables initially. If it is the mech, would this be the case?
  • jimothy78
    jimothy78 Posts: 1,407
    Ult wrote:
    Thank You. I will try that. It is smooth as silk with new cables initially. If it is the mech, would this be the case?

    hmm, I'd expect you to notice some degree of reoughness if it was the mech, so maybe it's not that afterall. However, it can't hurt to give it a bit of TLC, anyway, which may help lessen the overall friction.

    Have you tried the Shimano SP41 outer? It comes pre-lined with silicone grease, and the matching endcaps have little rubber seals at the end, so less dirt makes it's way inside. Don't grease the inners themselves - that can actually hold on to dirt and act as a carrier to transport it inside. PTFE- or Teflon-coated inners supposedly hold on to less dirt than standard ones, too, so might be worth a try.
  • Ult
    Ult Posts: 60
    Thank You . Will give those shimanos a go.

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