Help! Before I destroy my bike in frustration!

curium Posts: 815
edited May 2012 in Workshop
I gave my bike a clean up since I'm due to do a 100 mile ride on Sunday.

Commuting in the rain has caused a build up of crud and grease which has caused problems shifting and with the brakes so I gave it all a good clean and lube but I'm now struggling to get my front derailleur functioning.

The bike is a Specialized Tricross Sport with a Tiagra Triple front derailleur (50/39/30) and a Deore LX rear derailleur (12-25).

Since trying to reindex the front derailleur I've been unable to get it working properly. I've now replaced the cable and housing but I've made so many changes to try and get it working I now need a base setting to work from as I'm fire-fighting and going nowhere fast.

Either the cable is massively tight and I can barely move the lever to change gear or it's too slack and I can't get enough tension to shift into the outer ring. There have also been issues with the h & l screws in that I initially was confused about why the chain wouldn't move from the inner-ring to the middle ring and was using the l-screw to move the cage across when I should of been increasing the tension. The whole lot has been adjusted a million times and i'm frazzled and starting to panic about my ride :(


  • jgsi
    jgsi Posts: 5,062
    Park Tool tutorial ... djustments
    also use YouTube vids to double check your procedure.
    When on the innermost ring, the tension on the cable is its least.. meaning, not exactly slack but definitely not tight!

    If you are still having issues, eg the shifter is not clicking as you want it to, then a failed shifter cannot be ruled out.
  • keef66
    keef66 Posts: 13,123
    Visit Shimano Techdocs and look at the relevant Service Instructions. That will tell you how to set it up from scratch.

    From memory I think:
    1) set the lower limit screw so the mech is in the right position over the smallest chainring
    2) ensure the shifter is fully downshifted
    3) attach cable at the mech removing any slack. Hand tight is enough.
    4) check functioning of upshifts. Tweak barrel adjuster if neccessary to fine tune.
    5) set the upper limit screw to prevent overshifting beyond the largest chainring
  • onbike 1939
    onbike 1939 Posts: 708
    As this is a road triple chain-set, the cable tension should be set by placing the chain on the middle ring and adjusting the cable tension so that the chain just misses the inner plate of the cage.
    As has been said, Parktool repair section is very helpful.
  • keef66
    keef66 Posts: 13,123
    Mine's a triple. Shows how good my memory is!
  • arlowood
    arlowood Posts: 2,561
    This video is quite good despite the guy suffering from chronic catarrh.

    It's also a mountain bike front crankset but the principles are the same
  • Twostage
    Twostage Posts: 987
    Like Keef66 says go to the shimano tech docs and follow the instructions exactly.
  • desweller
    desweller Posts: 5,175
    Chances are the derailleur is binding as a result of all the rubbish in the pivots.

    Time for a flush with good old WD40.

    Release the cable clamp so you can move the derailleur with your hand. If it's difficult to move and does not feel smooth, apply a generous dose of WD40 to the pivots and manually push it through its full range of motion several times until it loosens up. Then mop up the excess fluid, wait for 30 minutes for the solvents to evaporate and then run some heavier oil (e.g. any motor oil) into the pivots to help them resist ingress of dirt in the future.

    Now you can start with the indexing as indicated above.
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  • curium
    curium Posts: 815
    Cheers guy! I'll have another crack tomorrow.
  • curium
    curium Posts: 815
    Managed to sort it but the method for success is different to the conventional methods advocated.

    I clicked the lever up to the highest gear. Passed the gear cable into the clamp-screw and pulled the derailleur out so it was over the big-ring while I tightened the clamp-screw. After that I basically only needed to make some minor adjustments with the barrel-adjuster and the H & L screws.

    Cost me 3 gear cables though as before I hit upon the above technique the constant tightening and loosening of the clamp-screw just destroyed the cables due to strands snapping and unravelling.
  • term1te
    term1te Posts: 1,462
    Just a thought, if it is a clamp on front mech, did it get moved around the seat tube at all whilst changing the cables, cleaning, etc.? If the lifting plates are not parallel to the chainrings, you will have trouble with the gear changes. Equally, if the whole mech got moved up or down on the seat tube, you'll have problems getting it to work properly.