shimano st 6703 problem...

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  • Peetee
    Peetee Posts: 20
    He we go with another resurection!
    It's happening to a bike I have in for repair too - a 2013 Cube Agree. before i saw it the chap had a ongoing issue with the gear cable routing. The bike had not been supplied with the correct push-in BB cable guide and the cable was taking a sharp bend on the way out of the frame bearing on the tube lip and the Crank axle en-route! I believe the present shifter issue may result from undue force being applied for the period of time that this crappy set-up was used putting too much load on the mechanism. I am going to look into it and report back BUT I need to let everyone know about another issue i have had in the past with 105 10 speed shifters which, given that externally at least they look very similar, could just as easily affect Ultegra's.
    If you ride the hoods with a firm grip all around the lever then dont be suprised if the internal mechanism starts shaving minute bits of rubber off the hoods (the lever body does nothing to protect the mechanism in certain areas). If you are unlucky these bits of rubber get onto the inner cable, cause friction and the cable does not return with the rotation of the mechanism on a down-shift. When you upshift again the cable can then foul the mechanism, kink, and start to fray. Before long you have a snapped cable and a real mess to sort out.

    Got 7 speed downtube shifters? Keep 'em! :wink:
  • koen.dens
    koen.dens Posts: 1
    ANOpax said:


    So, let's start with the basic design. There is a conventionally threaded hex head machine screw which enters the shifter body from the rear. You can see the head of this screw when you look at the back of the shifter. This machine screw goes through the long axis of the indexing mechanism and locates through another hole in the shifter body just behind the levers. The machine screw then enters the threaded aluminium piece which I and several other posters have found drops out when the shifter 'breaks'. The threaded aluminium piece is effectively the 'nut' which holds the whole assembly in the right place in the shifter body. When the aluminium 'nut' works loose and falls out, there is enough play in the locating hole in the shifter body for the machine screw to shift its alignment which throws the alignment of the indexing mechanism out and causes it to jam or stop downshifting.


    I managed to fix my shifter by taping the levers in the open position to give me access to the space behind the levers. I then taped the aluminium 'nut' to the end of an allen key, dropped it down onto the exposed end of the machine screw, tightened up the machine screw from the back of the shifter and voila, the shifter is working again.


    Thanks for this post! I was able to repair a stuck shifter with your explanation. Some pictures to clarify.




    This video might help too though you probably don't need to disassamble everything: https://www.youtube.com/watch?v=wJj6dASBMN0

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