New gear cable

bikeit65
bikeit65 Posts: 995
edited September 2014 in Workshop
When replacing the rear gear cable how far in / out should the adjuster barrel be, fully screwed in / out, or half way, when pulling the cable before you tighten the cable clamp bolt how much tension should be on the cable?
https://www.instagram.com/seanmcgrathphotography/
Trek Domane SL7 GEN4
Planet X RT58
Cannondale CAAD 10 2012.
Pain.. Is weakness leaving the body.

HATING LIFE-CYCLES FROM 2011

Comments

  • I start with the adjuster about half way and just another tension to remove any ´slack´.
  • rolf_f
    rolf_f Posts: 16,015
    Minimum tension that works - I think people tend to wind the cable in so it is super taught. Which IME leads to crappy shifting. A relatively slack cable allows the chain to shift nicely without any clunkery.
    Faster than a tent.......
  • Thanks folks, if i pull the cable with my hand so there is no slack on the cable will that be enough tension on the cable before i tighten the cable clamp?
    https://www.instagram.com/seanmcgrathphotography/
    Trek Domane SL7 GEN4
    Planet X RT58
    Cannondale CAAD 10 2012.
    Pain.. Is weakness leaving the body.

    HATING LIFE-CYCLES FROM 2011
  • rolf_f
    rolf_f Posts: 16,015
    Bikeit65 wrote:
    Thanks folks, if i pull the cable with my hand so there is no slack on the cable will that be enough tension on the cable before i tighten the cable clamp?

    I tend to use pliers to pull the cable a bit more taught than hand pull only just because the resistance through the cables and BB guide seems to result in it turning out slacker than I thought it was before doing the bolt up. You can then tweak the barrel adjusters to get the downshift feeling right (which is more sensitive to poor tensioning than the upshift). This is where having a bike stand really pays off!
    Faster than a tent.......
  • desweller
    desweller Posts: 5,175
    Rolf F wrote:
    Minimum tension that works - I think people tend to wind the cable in so it is super taught. Which IME leads to crappy shifting. A relatively slack cable allows the chain to shift nicely without any clunkery.

    I think you'll find that, if you consider what's actually going on in your derailleur and cable run, you'll want to reconsider that statement...;)
    - - - - - - - - - -
    On Strava.{/url}
  • rolf_f
    rolf_f Posts: 16,015
    DesWeller wrote:
    Rolf F wrote:
    Minimum tension that works - I think people tend to wind the cable in so it is super taught. Which IME leads to crappy shifting. A relatively slack cable allows the chain to shift nicely without any clunkery.

    I think you'll find that, if you consider what's actually going on in your derailleur and cable run, you'll want to reconsider that statement...;)

    Not unless you elaborate! I do know what you are getting at though. By slack I don't mean enough spare cable to lasso a horse with! It's more about not having so much tension that you can put a bow to the cable and get a tune out of it. There is a natural tendency for people do deal with poor shifting by increasing the tension when often the reverse is needed. Obviously, this matters more for the front mech than the rear.

    Of course, the question is about cable tension when bolting up so it's only relevant with regard to the small chainring, smallest sprocket.
    Faster than a tent.......
  • desweller
    desweller Posts: 5,175
    Rolf F wrote:
    DesWeller wrote:
    Rolf F wrote:
    Minimum tension that works - I think people tend to wind the cable in so it is super taught. Which IME leads to crappy shifting. A relatively slack cable allows the chain to shift nicely without any clunkery.

    I think you'll find that, if you consider what's actually going on in your derailleur and cable run, you'll want to reconsider that statement...;)

    Not unless you elaborate! I do know what you are getting at though. By slack I don't mean enough spare cable to lasso a horse with! It's more about not having so much tension that you can put a bow to the cable and get a tune out of it. There is a natural tendency for people do deal with poor shifting by increasing the tension when often the reverse is needed. Obviously, this matters more for the front mech than the rear.

    Of course, the question is about cable tension when bolting up so it's only relevant with regard to the small chainring, smallest sprocket.

    The derailleur return spring determines the tension in the system.

    For the derailleur return spring, F=kx, right? And x is always the same for a given gear, because x is the derailleur position. So F (cable tension) is also always the same for a given derailleur position.

    When you adjust the barrel adjuster with a new cable, you're just putting it back to the same place as it was with the old cable.
    - - - - - - - - - -
    On Strava.{/url}
  • Bikeit65 wrote:
    Thanks folks, if i pull the cable with my hand so there is no slack on the cable will that be enough tension on the cable before i tighten the cable clamp?
    Depends on your strength. With practice you'll find a method that works for you. I pull hard on the cable by hand with the adjuster screwed all the way in when clamping the cable. Then it will usually take 2-3 turns out with the adjuster to have the proper tension. That's just me though. Some have more strength and/or some like to use pliers to pull the cable with the adjuster unscrewed a couple of turns when clamping.
  • Folks all sorted, i left the adjuster barrel about three turns out and pulled on the cable just to take the slack out of it, a few quarter turns counter clockwise and the shifting is sweet, took it for a test ride and a further quarter turn clockwise and all is well,
    Thanks for your help.
    https://www.instagram.com/seanmcgrathphotography/
    Trek Domane SL7 GEN4
    Planet X RT58
    Cannondale CAAD 10 2012.
    Pain.. Is weakness leaving the body.

    HATING LIFE-CYCLES FROM 2011