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Rear Mech not able to Pull Cable Through Frame

ben_b1ben_b1 Posts: 9
in Workshop
Hi All,
I have a ribble R872 with around 20000km on it (Many of which have been wet winter miles) Over time the shifting has deterioated as the bike has got older. When I replace the cables now the shifting does not return to a decent standard as it used to. Even after putting new cables in the bike, when setting the gears up the mech still struggles to pull the cable through the bike as it shifts towards the 11 tooth. The resistance seems to come from with-in the chain stay and the down tube. The mech is not the problem as it has been serviced and works well of the bike.

Recently the cable has snapped a couple of times in the shifter and has also become jammed in the shifter due to a build up of slack in the cable caused by the mech not being able to pull the cable through the frame as it is released by the shifter.

My thoughts were that the cable could either be rubbing with the inside of the frame or that there may be a lot of dirt in the frame (this seems unlikely though as cables come out of the bike relatively clean).

I am hesitant to take the bike to the local bike shop as they may just replace the cable, say it works then the problem will be back after a couple of rides.

If anyone has any ideas or advice, or has similar problems i would be grateful to hear from you.

Thanks

Ben

Posts

  • me-109me-109 Posts: 1,871
    Any issues fitting the new cables? Any restrictions or resistance felt when feeding the cable through the internal sections? That might give some indication. If so, you could try blasting some aerosol fluid through with a straw attachment - GT85, WD40, penetrating spray, anything that will soften and flush out the muck.
  • ben_b1ben_b1 Posts: 9
    me-109 said:

    Any issues fitting the new cables? Any restrictions or resistance felt when feeding the cable through the internal sections? That might give some indication. If so, you could try blasting some aerosol fluid through with a straw attachment - GT85, WD40, penetrating spray, anything that will soften and flush out the muck.

    The cable is harder to feed through the frame than it used to be, would you just spray the WD40 in at each end. and how would you remove dislodged dirt from the frame after spaying a penetrating oil in?
  • darkhairedlorddarkhairedlord Posts: 7,180
    edited August 2020
    I have an r872. It's the nylon tube that runs from through the chain stay, it can get gunked up and it can also wear through. Ifcyour tube is missing, that is the problem! Both gear cables should have them. If they are there then Try pulling a cleaned up old cable back an forth with wd40 on it to clear it out. If that doesn't work, pull the tube out and reachable with a jagwire elite cable set. These have a liner that runs the length of the cable. I bought a set from wiggle last week but haven't got around to fitting yet.
  • david37david37 Posts: 1,313
    Replace cable outers. Ditch the tubes or put a short length of new in if required. In fact given the cost of a couple of quid im surprised people dont change the outer every time.
  • ben_b1ben_b1 Posts: 9
    darkhairedlord said:

    I have an r872. It's the nylon tube that runs from through the chain stay, it can get gunked up and it can also wear through. Ifcyour tube is missing, that is the problem! Both gear cables should have them. If they are there then Try pulling a cleaned up old cable back an forth with wd40 on it to clear it out. If that doesn't work, pull the tube out and reachable with a jagwire elite cable set. These have a liner that runs the length of the cable. I bought a set from wiggle last week but haven't got around to fitting yet.

    There is no housing running the length of my chain stay which could be a contributor as this does seem to be the area with the most resistance. What model / age of r872 do you have? I'll have a look at this jagwire cable set you mentioned.
  • darkhairedlorddarkhairedlord Posts: 7,180
    I just swapped out the cables this weekend and work fine. Mine is pre-2014 I think. The version with the 31.8mm seat tube and 51,5mm crown bearing.
  • ben_b1ben_b1 Posts: 9
    Think mine is the model after that, will ask Ribble is there should be a tube
  • darkhairedlorddarkhairedlord Posts: 7,180
    There is a xable outlet on the chain stay, secured with a screw, pop the outlet off and it should have a tube running from there.
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