Hi/Lo Limit Screws and mechanical issues!

Brian B
Brian B Posts: 2,071
edited March 2015 in Workshop
I have an issue with my new bike which has Ultegra 6800 in that one moment the gears were working great then blam they all went to pot. The front derailleur now moves so far both ways as if its totally ignoring the hi/low limit screws (and they have not been touched) and I have to be careful when shifting from the 50 to the 34 to avoid the chain jumping off and the last trim option on the 34 now jumps much more than before.

Further to this if I want to change up into the 50 ring I have to push on the derailleur by hand and then operate the shifter as the FD is now so far back that the lever cant seem to force it outwards without my help - its kind of hard to explain.

The bike's going back to the maker and they have been great and rapid response from then but was wondering if any on here has any idea what has went wrong - here are a few options I thought :-

I initially thought the cable had slipped but it has not and anyway even if it had the limits of the mech should not be effected as they are set with the cable off - right?

Something has went wrong with the FD and it now ignores the set limits and moving way much in either direction than it has before - like a pin or screw is missing. Compared it to my other bike which has the same group set and all looks the same apart from the huge shift.

There is something wrong with the shifter internals but I have even less of a clue about that than I do front mechs.

Any thoughts appreciated

Ps can you move limit screws after the bike has been set up. I have been tempted to try but just going to leave for manufacturer to see without my interference but was just wondering
Brian B.


  • jgsi
    jgsi Posts: 5,062
    http://www.parktool.com/blog/repair-hel ... djustments
    is a clear and concise guide.
    You seem confident that your bike maker will sort the FD out this time however for the future I'd really recommend learning to adjust yourself. The FD is one component that is pretty straightforward to suss.
    The cable moves/released by the shifter the mech moves .. the chain moves.. the limit screws are just stoppers to ensure chain is not shipped.
    They really are not rockets requiring science.
    Or go to di2
  • trailflow
    trailflow Posts: 1,311
    edited March 2015
    Its not the bike manufacturers responsibilty to set the FD up if it goes out of adjustment. The FD and shifter both broken seems unlikely.
    Your first step should be reading the Shimano 6800 set up manual.
    http://www.google.co.uk/url?sa=t&rct=j& ... 24&cad=rja

    Then watching Youtube video's and reading the forums. Then if all else fails you should take it to a bike shop. and ask if they can show you how to do it. Seeing it done in person is a lot better than text.

    The 6800 FD installation is a little different to other derailleurs so the park tools tutorial above may not help.

    If the FD is moving too far then the limit screws need to be turned inwards. Thats what they do prevent the cage moving to far. Thats the first thing you should try. Its not uncommon for the limits screws to move. It shouldnt happen frequently, but it does happen. They will need re-adjustment at some point in time. They are not set and forget. Don't be afraid to turn the limit screws, thats what they are there for. Its OK to turn them with the cable attached.

    If the shifter needs too much force to shift. Then the cable tension may not be right or the cable may be attached incorrectly. There are two clamp positions to choose from.

    Also the derailleur may have dropped and is touching the large chainring. Without pictures of your setup its hard to know whats wrong.

    i made a set up tutorial in this thread you might want to try
  • Brian B
    Brian B Posts: 2,071
    Not the most helpful of replies JGSI and I am sure it will get fixed as its only days old. I can adjust gears and I have watched videos on how to set up and practiced on an old bike but I think there is an issue with the FD. In no way should gears go from working great one minute to complete rubbish. As said I have the same group set on another bike and its behaving way different. The front lever won't even shift at all without my help.

    I usually pay my LBS to do things like this as its keeps them in business and its keeps amateurs setting up wrongly and crashing as a result of a thrown chain.

    Thanks trail flow my above comment is about the initial post. Limit screws appear to be untouched as they were sitting pretty flush to begin with and no would both screws move at the same time. With my other bike I sat with my LBS mechanic and he showed me how according to the Shimano guide that what route the cable should be attached depending in the angle of how it comes around the BB. I have discussed this with the REP and alls is how it should be.

    Derailleur height has not changed either and sitting perfect according to the shimano set up
    Brian B.
  • trailflow
    trailflow Posts: 1,311
    They may look flush but all it takes is a tiny bit of movement to make a difference. The gap between the cage and chain will tell you if it needs adjustment or not. It should be around 0.5/1mm, and as close to the chain as possible without rubbing/noise.

    Other things to check are

    Any ferrules are seated in the frame and shifter lever properly
    The cable is in the shifter mechanism properly
    No kinks in the cable anywhere or damage to the cable causng fraying
    No burrs on the cable outer ends causing unwanted friction
    If there is a bb guide make sure its secure and not moving around
    and lubing the shifter internals may help
  • dgunthor
    dgunthor Posts: 644
    sounds like the front mech cable has stretched and the near limit screw (small chainring) maybe wasn't setup correctly initially

    follow the park guide above to setup or ask the shop you got it from to sort it out (should be free gear service to resolve initial cable stretch)
  • desweller
    desweller Posts: 5,175
    If it's a sudden big change on a new bike then there could be other factors at play. Poorly formed limit screw thread on the derailleur body or a big bit of swarf that's caused someone to set an incorrect limit are a couple of things that spring to mind.
    - - - - - - - - - -
    On Strava.{/url}
  • Brian B
    Brian B Posts: 2,071
    All thanks for all the replies - even JGSI as no reply would be worse ;)

    I hate tinkering with a brand new bike but I was wrong and the limit screw WAS to blame. Adjusted the mech back to where it should be according to the online guide and its working perfect. Will monitor it over the next week or so to see its does not move again.
    Brian B.