Problems getting front mech cable through carbon frame – help!

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  • Problems getting front mech cable through carbon frame – help!
  • theflatboy
    Member

    In the process of swapping (broken – thanks Shimano) STI shifter, stupidly pulled old cable out of frame and now am unable to get new cable through the hole behind the BB shell.

    Frame is Specialized Roubaix, going through either top or bottom cable hole the cable goes in a few mm and then hits an obstruction. I have been trying all evening to get the cable through to no avail… any bright ideas welcome!

    theflatboy
    Member

    Ok, I’ve slept on it… And still no luck. My thinking now is first to take off the cable guide under the BB in the hope that will leave more room to manoeuvre and then feed it back through, failing that to take out the BB to see if it gives any better access to feed it through.

    Any other bright ideas gratefully received, otherwise it’s to the LBS admitting defeat!

    I would like to get all the bike designers who think internal routing is a good idea, put them in a field, and shoot them.

    APF

    steve_b77
    Member

    Feed it through from the bb end first to the exit point on the down tube (?) super glue a length of cotton to it, pull it back through, superglue cotton to new cable and pull it through the right way.

    Get a long thin stainless rod or copper rod (twin & earth stripped is ideal) and thread that through and then repeat the cotton technique

    theflatboy
    Member

    Thanks for the suggestion. I worded it slightly misleadingly – it’s actually external routing down under the down tube, then the point I’m stuck on is after it’s run round the BB shell where the cable runs through the frame to the front mech. There is just no way to get the cable to go anywhere other than a few mm in from either side. There’s solid obstruction in the way…

    Premier Icon wwaswas
    Subscriber

    if it feels blocked use an old spoke to force through and clear it.

    theflatboy
    Member

    I did try that with a small Allen key but was virtually bending the key with no discernible progress. I think that the route through must be on an angle, but god knows how to persuade the cable to follow the invisible route through…

    I think taking BB out may be my only hope, if that doesn’t work its either going out of the window or to the LBS. maybe both… πŸ™

    Baznav
    Member

    Removing BB gives you no more access to that area.

    theflatboy
    Member

    Cheers, baz, useful to know.

    I’ve bitten the bullet and taken it to the bike shop… I feel simultaneously emasculated and liberated, quite an interesting feeling!

    I’m just glad it’s going to be sorted for the weekend, I was not expecting it to be so complicated!

    steve_b77
    Member

    The bb will be in an aluminium insert so you won’t get access that way.

    My last bike had the same issue, the hole is full of road grime / salt. Turn it upside down, fill it with WD40 (the hole that is) leave it for a bit, then use a small 2-2.5mm drill bit and twist it in and out of the crap. It’ll clear out eventually and all will be good.

    theflatboy
    Member

    That’s what I was wondering. Any ideas on best way to protect it from happening in future? How can you defend that area other than guards…?

    remove the bottom bracket cable guides. remove any hardware bolted to the frame and the rear plastic “banana”

    use an inner brake cable (its much stiffer than gear cable) and start at the top of the downtube. Feed the cable through until it pops out of the BB area. then slide a long length of internal cable routing “pipe” onto the end of the brake cable (it will be a snug fit) and drag the cable back up the DT taking the pipe with it. Tape the end of the pipe where it comes out of the DT, so it does not fall down once your remove the cable.

    you can now install the hardware and feed your inner gear cable through. Always suggest doing the rear mech first. for the chainstay its a little tricker. Rotate the frame / bike in the workstand so the back wheel is up in the air (vertical). Take your inner brake cable again and start next to the BB, feed it up the inside of the stay. Sometimes you have to twizzle the cable as you feed it, other times you get lucky and it finds the exit hole above the dropout. Then plug in more long pipe and drag backwards. Tape the end next to the BB, and remove the brake inner cable

    Then feed your gear inner from the DT / BB area into this pipe after threading the wire through the right cable guide (some Roubaix use a single cable guide under the BB). Once the wire is through and out the dropout, you can pull the pipe back out of the dropout and trim it to length, as it will be too long. Put the pipe back onto the cable, install the banana and finally the loop of rear gear outer

    Sometimes you may have more success in feeding the inner brake cable the other way, but you tend to have to chop off the brake nipple, whatever works is worth sacrifcying a cable

    Front mech is easier as you just have the procedure for the DT. Once cable is through, run it through the left cable guide and then bolt both guides in place using the cover plate and bolt

    If you ever find your frame is clogged up with muck / grassy stuff / etc. I’d strip the frame, flush with warm soapy water, rinse with warm clean water and dry overnight before rebuilding

    I work in a Specialized Concept Store as a bike mechanic, and have worked on 300+ warranty / crash replacement / service jobs on Tarmac, Venge, Roubaix in case you are wondering πŸ˜‰

    theflatboy
    Member

    Excellent stuff, the pro low-down! Cheers, I will print this off and stick it in the tool box for future reference. πŸ™‚

    johnnoone
    Member

    I had the same problem on my 2011 Pinarello FP2 (it’s a straight hole through the frame just behind the BB) – I’ve just used the small drill bit and warm water technique to clear out mine. Tip: don’t ‘push’ from both ends, you’ll just compound whatever’s in there. I couldn’t believe how such a tiny bit of mud/gunk had caused me such a headache – thanks due to the forum posters πŸ™‚

    theflatboy
    Member

    I read the thread title and was about to empathise with this thread… πŸ˜†

    It still gives me nightmares, I don’t think I’ve ever come so close to throwing a bike through a window!

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