Planet X Pro Carbon - Front Mech Cable

bbking83
bbking83 Posts: 12
edited October 2016 in Workshop
Hi

Currently building a bike from a second hand Planet X Pro Carbon frame, and brand new full Tiagra 4700 groupset using the SL-4700 flat bar shifters.

The problem i am having is that the hole in the frame near the bottom bracket where the front mech cable comes through, seems to me as if it is too far forward. This is leading to issues where the cable is catching on part of the mech.

Stock google image to show where the cable is catching on: ae1f8bfd854c4c719d8bb3c457119490.png

Lastly.. I have uploaded a video to show exactly how badly it is catching. Not a nice noise and i can't imagine that cable lasting very long like that!

https://www.youtube.com/watch?v=eLCT6rwiUkI

Thanks in advance

Comments

  • fenix
    fenix Posts: 5,437
    Can you secure the cable between the washer and nut rather than the washer and mech ? Or possibly the other side of the mech ?
  • diamonddog
    diamonddog Posts: 3,426
    Mine is SRAM and fed through the frame side (back) of the mech, this moves it away from where your one catches.
  • arlowood
    arlowood Posts: 2,561
    Your post intrigued me as I built up a Pro Carbon frameset earlier this year using 105 5800 which has the same "long throw" actuating arm on the front mech as the Tiagra 4700.

    26753058665_8f976a0aa0_z.jpg

    Must confess that I never noticed the cable fouling issue when the build was completed so I popped into the garage to have a look. Like yours my cable appears to be catching on the same part of the 105 FD but I have not noticed the same clicking noise as you show on your video.

    Have completed about 700 miles with the cable in that situation but can't see any obvious wear.

    If it worries you there may be a possibility to fit a washer between the cable and the mech arm to push the cable a little further away but that would depend on there being sufficient length of thread on the cable fixing bolt
  • svetty
    svetty Posts: 1,904
    As above - I'd sugggest adding an extra washer so that the cable is pinched between 2 washers rather than between single washer and mech body
    FFS! Harden up and grow a pair :D
  • bbking83
    bbking83 Posts: 12
    Thanks for all the replies!!

    I have had another tinker after your suggestions, I have managed to borrow an washer from an old front mech.

    First I tried the cable in the same position but with the washer, was ok-ish... I tried again, this time moving the cable so it was on the other side of the screw thread (closer to the frame, pictured below).

    Clearance is super tight, i mean you could not slip a cats whisker between the cable and the mech, it makes no noise and am happy with the result.

    However one interesting thing I noticed trying both positions... The down shift seems a bit quieter? :D This is either me being a noob and not getting the same cable tensions or is it possible that the position of the cable on the mech could make such a difference? i did try adjusting cable tension to test but i could not repeat this result.

    VoPKHaI.jpg
  • bbking83
    bbking83 Posts: 12
    arlowood That is a nice looking bike mate! :D I wanted to build this bike on 105 but as it is a flat bar road bike i am building, certain compatibility issues would not allow me to do so with the sl-4700 flat bar shifters! :(

    Whole bike is Tiagra, however I did buy 105 5800 brake callipers as they seem to be a big improvement over the tiagra brakes. However since i don't have the original forks, the calliper on the front is not long enough so now i need new forks before i can use the 105's :( This bike build has been nothing but problems! :(
  • The Rookie
    The Rookie Posts: 27,812
    Be careful routing the cable like that as it changes the cable pull to mech movement ratio slightly, may affect the indexing.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • diamonddog
    diamonddog Posts: 3,426
    Good result, as I said in my other post my SRAM one was set up like that from the day I picked it up from PX and has been fine for the last few years and the Shimano on the turbo bike is the same.
  • svetty
    svetty Posts: 1,904
    bbking83 wrote:
    However one interesting thing I noticed trying both positions... The down shift seems a bit quieter? :D This is either me being a noob and not getting the same cable tensions or is it possible that the position of the cable on the mech could make such a difference? i did try adjusting cable tension to test but i could not repeat this result.

    Likely a gnats less cable tension
    FFS! Harden up and grow a pair :D
  • arlowood
    arlowood Posts: 2,561
    bbking83 wrote:
    arlowood That is a nice looking bike mate! :D I wanted to build this bike on 105 but as it is a flat bar road bike i am building, certain compatibility issues would not allow me to do so with the sl-4700 flat bar shifters! :(

    If you want to stick with 10 speed there are options that will let you run the old 105 5700 mechs with flat bar shifters. I used these on a build for my grandson a couple of years back.:-

    http://www.tweekscycles.com/Product.do? ... oCa67w_wcB

    worked a treat with 105 5700 front and rear mechs.

    A move up to 105 5800 is still a possibility with the availability of these flat bar shifters

    https://www.evanscycles.com/shimano-rs7 ... s-EV220651


    Those will be fine with the 5800 front and rear mechs

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