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Front Chain keeps coming off and rear indexing

sherersherer Posts: 2,460
edited October 2009 in Workshop
Had a few issues on the last sportive I did and to be honest i've never been fully happy with the indexing on the rear since I got the bike. I have a Trek Madone 4.7 with full Ultegra in a triple. I've had the gearing indexed at the rear about 4 times now. I know the cables will stretch but after 500 miles I thought it should have settled down by now.

As I am a weed I have also changed the triple at the front from a 30 to a 28 and that has been a really big help in my riding, I can keep going now instead of walking so that at least means I am improving now on the longer rides rather than walking and not helping. The problem I get is when I change down to either the 39 or the 28 at the front, the front chain keeps dropping off, or it will skip the 39 out and go to the lowest ring.

Am thinking of giving another LBS a go as the I got it from have taken a look about 3 times at the indexing and not solved it.

Is there anything I can do to check this myself before I take it into the LBS.

I do only ride the bike for events and once before to make sure it's ok, I have another bike for day to day use


  • On the front derailleur there are two screws, hopefully marked L and H. These control the inner and outer limits of the chain. Usually, the L screw is the one nearest the frame. You should turn the L screw 1/4 clockwise. Check and if necessary, repeat.

    Of course, you might have to re-position the derailleur on the frame. Hopefully you'll be able to see this video which is a good explanation of what what you can try at home
    The ultimate cruelty of love's pinions
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