New rear mech problems

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  • New rear mech problems
  • belugabob

    Brake cable outers are not the same as gear cable outers – that’s why they have different names.

    Whilst I’m not sure this would produce the symptoms that you’re seeing, the accuracy of gear changes will be affected by using brake cable outers. (And using gear outers for brakes is very dangerous, as the outers can split under the much higher pressures involved.)

    Use of ferrules is pretty much obligatory, to keep the ends of the outers from fraying, or getting deformed.


    Instant and certain death awaits when you use the wrong casing

    If your not a troll sure some proper advice will


    Hey guys! I’ve replaced my rear mech along with the gear cable and rubber sleeves. Now nothing happens when I shift with the STI shifter nor when I turn the barrel adjuster.
    I didnt use any “ferrules” for the rubber housings, is that relevant? -when I turn the barrel adjuster it doesn’t change the tension on the cable at all. I really have no idea what’s wrong. Even when I shift up with the STI shifter nothing happens.
    I used a “brake cable” cable for this but as its identical to the gear shifter cables I didnt think it mattered.
    Any ideas? Thanks in advance!!


    Brake cable outers are not the same as gear cable outers

    Whilst I’m not sure if the outers I’m using are brakes ones or gear ones, in my post I was referring to the actual metal cable. It’s a brake cable I’m using – since the cylindrical part which slots into the STI shifter is identical to the ones on the gear cables.

    Instant and certain death awaits when you use the wrong casing

    Damn, I thought I’d get away with using a “general” one. As I say above, the cable is a brake cable but about the casing I’m not sure.

    If your not a troll


    Premier Icon speedstar

    Brake cables and gear cables aren’t the same but i’m not sure if they’re interchangeable or not. I would use gear cables for gears as they also have the right “head” on the cable for inserting into the STI. The ferrules are vital as the give resistance to the cables when changing gear. Also, are you setting it right, with it in it’s lowest gear when tightening the cable? Do all of these things right first.

    Premier Icon kayak23

    Sounds to me as if you’ve somehow managed to put the cable into the shifter but not actually connect it,if that’s even possible.
    Brake cable inner wires have different nipples to gear ones too so probably wouldn’t physically fit into the shifter I’d have thought.

    Have you got ANY tension on the cable? Did you pull it taught before clamping it down on the mech?

    With respect, if you’re not sure how to do such a task,it might be a good idea to get someone to show you who has the experience .



    The head probably isn’t sitting in the shifter properly since you’re using a brake cable inner (they may look similar but they are definitely not identical).

    Each time you operate the shifter the cable rests in a different spot resulting in a different tension and no shift?

    Just a thought anyway, use a gear inner…


    118118 bikeshop


    As above if you’ve used the wrong inner then the end won’t be locating in the shifter properly. There’s also the possibility you haven’t located the outer through one of the cable end stops.

    As it’s a new rear mech you also have to use the high and low adjuster screws to set the mech stop points, and adjust the b tension screw. If you haven’t done that first before tightening the cable then the mech won’t shift properly. The barrel adjuster is for fine tuning really.

    Bike radar also have a good video on mech set up.

    Take you’re time, follow the process, use the right cables and you will get there.


    Also, are you setting it right, with it in it’s lowest gear when tightening the cable?

    @speedstar Yup. I have it in the smallest cog when tightening the cable.
    But you’re probably right. The inner cables won’t be the same (the heads) and so won’t fit in the STI correctly. I don’t know what made me think that they’d be interchangeable. Plus, I didn’t know the importance of the ferrules

    @kayak23 Me trying to be cheap I guess and thinking a brake cable inner would do me for gear changing. I thought the nipple which slots into the STI were the same.
    And yes, I did pull it taught before clamping the cable but that actually did more damage and I had to remove the STI and dismantle because the cable got stuck inside!
    I am actually at the point of bringing it into the workshop 🙁

    @haze Exactly. I won’t be a cheapskate in future. That and do my research better. I had actually changed the wires before but must have used a proper gear inner when doing it.

    @Gary M Dead right. I’ve used brake inners and outers instead of gear ones (combination of me thinking they did the same job and being a cheapskate). You wouldn’t have the exact link to that bikeradar video would you?
    It’s a trek road bike I have and the rear mech is shimano 105.

    Thanks very much to all. Frustrating to make such newbie mistakes having been years on the bike but there you go.
    The point I’m at now is a dismantled STI. Since it was a gear inner cable I used with the incorrect head, it managed to get lodged inside and I had to take the shifter apart to get it out. Now I’m pretty sure I need one of these spring mounting tools to put it back together again:
    Anyone have experience putting an STI back togther?

    Thanks very much for the advice guys, really appreciate it


    If you good ‘setting up a rear derailleur’ it’s the first video/link to come up.

    It’s a YouTube link.

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