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Help with setting up Front Mech.

newburb_1968newburb_1968 Posts: 114
edited January 2009 in Workshop
Hi all
Once again I am after your "Know How" side of things...

I am having some trouble with putting on a new Triple Front Mech on.

The problem I have is once I leave it 1-3mm clearance, I connect the cable up and try moving the Shifter to the high ring I can't move the shifter to take it to the high ring.

It's seems that the whole front mech is blocked against the chainring which won't allow it too move.

Could anyone give me some advice on setting this up, or had a similar problem and what they had to do to get around the problem.
They other thing is when you look down the frame are they set on straight or at a slight angle.....

Once again any help would be useful, because I want to get out there some time today...........Thanks barry

Posts

  • whyamiherewhyamihere Posts: 7,520
    Have you set the limits of the mech to allow it to move far enough?
  • No, I assumed that was fine tuning.

    My assumption was 1-3mmm large chainring, drop back to small chainring, connect cable and it should move and then fine tuning.

    Then use the shift to ensure the movement.........which then becomes a problem because it feels like I'm pushing against a wall (Which happens to be the inner plate against the chainring).

    Are you saying that before moving the shifter set the lower limit...

    Sorry for be a numpty....it's one of these things that once you've done it then you don't think twice about it.
    Regards
    Barry
  • topdudetopdude Posts: 1,557
    Are you sure it's a Triple front mech and is the shifter triple compatible :?:

    Disconnect the cable from the mech, pull on the end of the cable and operate the shifter through it's whole range. Does it have three positions up and down, (also maybe some intermediate trim positions) if so your shifter is ok.

    While disconnected move the mech by hand, does it move far enough to cover all three chainrings ( check the limit screws as mentioned above).

    If the above checks out let the mech sit on the limit screw over the smallest chainring, make sure the shifter is in it's lowest position, connect the cable to the mech and pull on it to remove all slack. Tighten the bolt and test the gear change.
    He is not the messiah, he is a very naughty boy !!
  • whyamiherewhyamihere Posts: 7,520
    If you're sure it's the mech hitting the chainring then there's no other option but to move it higher. However, it shouldn't be hitting, as you have set the height correctly.

    The high limit, if set too far in, will prevent the mech from moving far enough to shift onto the large chainring, and it will feel like you're hitting a wall as you describe. Fine tuning the limits is best done once the mech is shifting, but they need to be basically right as the first step.
  • Thanks.....I am off to have another play.

    I'll let you know the outcome.
    Thanks again
  • Hi
    I finally got it going briefly, I think it had something to do with the cable tension??? (I'm still waiting for cable adjusters).

    So I only re-align the gear cable now (I had a spare new cable so I thought perhaps I might as well change this) dropped it a bit lower, done a bit of the adjusting and BINGO it worked......it got all the way up to the big boy... 8)

    So let's see if it drops down to the little ring......this is a bit hard I'll give it a little extra "SNAP", "CRACKLE" & "POP" No more lovely clicking from the STI's...........I think I might have done more damage.

    A nice easy job turns into the everyday nightmare, me thinks it a trip to the bike shop and now having to wait a few days.

    Has anyone had the same affect, would the STI be knackered, OHHHH I wished I never took on the task...
    Any help!
    Regards
    Barry
  • topdudetopdude Posts: 1,557
    Have you done this as suggested ?
    Disconnect the cable from the mech, pull on the end of the cable and operate the shifter through it's whole range. Does it have three positions up and down, (also maybe some intermediate trim positions) if so your shifter is ok.
    He is not the messiah, he is a very naughty boy !!
  • Better to have a look here before doing anything else.

    http://www.parktool.com/repair/readhowto.asp?id=75
  • carefulcareful Posts: 720
    Don't know if it will help, but I always find it a lot easier to do the initial set-up with the chain removed. This way it is easy to get the height/big ring clearence spot on.
  • Hi some good additional advice there.

    Next time I'll think twice before I put some extre pressure on the STI's it seems that on inspection I have damaged my left STI. :cry:

    Inside I have snapped a piece of plastic conector off within the Shifter, so this is turning out to be very expensive........

    I only changed my Chain last Saturday (After 4000miles) I thought it was time because I felt it slipping... The pin could not have slotted in correctly and allowed a part of the link to slip away leaving it to jam in the front mech...... which then while peddling bent the front mech in the chainring.......which forced me into renewing the Front Mech.....which I now screw up a STI.

    Now let's work out the price £15 chain, £1 pin, £23 front mech, £2 gear cable, £120 STI??,,,,,,,SO Changing a chain could cost up to £161 ooouch........

    Not including bar tape, rear gear cable & seat post over the previous few weeks which has taken me up to nearly £200.......

    What makes you think I should have gone to the LBS......

    Anyway to reduce my Pain does anyone know if I can buy a single left hand STI, rather than the pair....and if so where from?

    Regards
    Barry
  • whyamiherewhyamihere Posts: 7,520
    Let me guess... Tiagra STIs?

    How old's the bike? You might be able to get new ones under warranty.
  • 105's & 18mths old......Trek 1.7
  • MrChuckMrChuck Posts: 1,663
    Better to have a look here before doing anything else.

    http://www.parktool.com/repair/readhowto.asp?id=75

    +1. The Park Tools site is invaluable and if you follow the steps carefully you really can't go wrong.
  • whyamiherewhyamihere Posts: 7,520
    105's & 18mths old......Trek 1.7
    Ebay's your best bet then for getting just a left hand lever. A shop will only sell them as a pair.
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