Front Derailleur adjustment troubles

CTML
CTML Posts: 53
edited April 2009 in Workshop
Had a problem for a while whereby the chain is rubbing against right side of the front mech when on i'm on the highest cogs (on all 3 chainrings). Its a tiagra triple and I finally had the time to look over it today, refit it and change the cable but its still problematic.

While tweaking it, i found that the H-limit screw doesn't do anything which is screw that should solve my problem. Also, i don't have a trim feature on my drops for some reason.

I've already been through quite a few tutorial vids, webpages etc. although i have an idea of what i'm doing the bike doesn't seem to respond to the changes i make (except from the L-limit) so just wondering what you guys can advise me to do :(

Comments

  • rogsmer
    rogsmer Posts: 22
    sadly i have a double tiagra which has the same problem. recently i stopped being able to shift downwards without me having to kick it
  • CTML
    CTML Posts: 53
    rogsmer wrote:
    sadly i have a double tiagra which has the same problem. recently i stopped being able to shift downwards without me having to kick it

    yes, apparently its quite a 'common' problem on small sized bikes :roll:

    Have you fixed it? if so how?
  • careful
    careful Posts: 720
    If you are having the same problem with all three rings then the problem is not the H limit screw. This is intended only to stop the chain from being thrown past the large ring when you change from mid to large. All other adjustments are with the cable tension and it soulds like tightening yours a touch might do the trick. Try a quarter turn the cable adjuster if there is one. If not then you will need to tighten the cable at the grip. Cant remember if Tiagra shifters have a trim position.
  • onbike 1939
    onbike 1939 Posts: 708
    If the chain is rubbing on the inside of the right side then it sounds like the tension is too tight. With road triples you should start from the beginning and the Park tool site has a good explanation. With the chain on the smallest ring and the largest cog, the chain should just miss the inside plate of the cage. With the chain on the middle ring, and the largest cog the chain should just miss the inside plate of the cage and the tension of the cable should be set to ensure this. This amount of tension should then be right to avoid the rubbing that you describe.
  • CTML
    CTML Posts: 53
    Thanks for your prompt reply guys, actually I have been following the park tools instructions all along haha! I've just tried both tightening and loosening the tension (each by 1/2 turn). With a bit of trial and error the largest and smallest chainrings seem to be okay and doesn't rub, just. However, the middle chainring seems to still rub when i am on the outermost cogs from 6th onwards. My L screw is pretty much screwed down as much as it can go, whereas my H is about 5 turns looser. however, the gearchanges felt more clunky and different, i just can't seem to get it right. If i play around with the H screw, am i supposed to physically see the derailleur cage move like the L screw?

    P.S I don't have trim adjusters
  • onbike 1939
    onbike 1939 Posts: 708
    If you don't have trim adjusters then it's more difficult to get the small amount of movement required. You really should fit these, even in-line adjusters make the job easier and at best, with a triple, it can be tricky.
  • vitesse169
    vitesse169 Posts: 422
    Might I suggest that you don't use the highest/lowest gears on the mid ring & don't use the highest with the little ring - also the lowest with the big ring. With 9/10 sp gears the chain stretch sideways is very detremental to the life of the cain and the cassette...
  • CTML
    CTML Posts: 53
    i might get some inline adjustors, they seem cheap enough but will it actually make that much of a difference? Vitesse, i try not to cross the chains anyway but i do use my middle chainring no the higher cogs sometimes.
  • vitesse169
    vitesse169 Posts: 422
    CTML - I'm not much of an MTB'r, not sure if the in line adjusters is mtb thing.... I seem to remember a mate telling me some years ago not to use the 9/10 sp on the cassette with the little ring as it will bend the chain sideways shortening the life considerably. I don't use a triple on the road bikes but have noticed that on the little ring the 8/9 on the cassette makes the chain rub on the inside of the big ring. Having said that I can use the 1 on the cassette with the big ring with no problems.