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Ultegra FD-6703 question

Old 10-23-13, 05:00 PM
  #1  
bykemike 
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Ultegra FD-6703 question

I am working with a brand new Ultegra FD-6703 triple front braze on dr.

This is an all new 10 speed drive train, with matching Ultegra STI's. The only older component is the crank set but I checked the chain ring spacing with a new 10 speed crank and it is the same.

This is a 1984 vintage Italian frame (Ciooc) using the stock Campy BB.

When I am shifting from the intermediate front chain ring (39T) to the small chain ring (28T) the dr does not quite go far enough to get out of the way
of the chain when using the lowest three rear cogs.

I have the low adjustment screw backed out completely so adjustment isn't an issue. I am thinking of taking a little metal off a "tang" (for lack of a better term) to allow the cage
to go towards the frame an additional couple/three of thousandths of an inch and then reinstalling the low adjustment screw so it just touches.

Is it possible I am missing something here? Is my solution ok? I am sure it would work but it may throw the indexing of the STI off a bit.

Thanks

Mike
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Old 10-23-13, 05:08 PM
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CACycling
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Is the BB correct for the crankset and your chainline correct? If so, then check the angle of the FD to make sure it is parallel to the chainrings. Finally, make sure there is nothing else stopping the FD's travel (cable disconnected, limit screw backed all the way out and nothing else touching the FD that could keep it from moving). Only then would I consider modifications. Don't see the mod you propose causing an issue with indexing but look closely to make sure there would not be anything else preventing the FD cage from moving inboard.
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Old 10-23-13, 05:23 PM
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bykemike 
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Is the BB correct for the crankset
This is a concern for me. I am using the BB that came with the bike and there was a compact double on there vs the triple I am using. Do you think I need a longer spindle? If so it would only need to be just a tiny bit longer and I don't know if I could find one..vintage Campy and all.
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Old 10-23-13, 05:57 PM
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I know little about vintage Campagnolo, but I presume that you have an ISO square taper crank. Those generally require BB's with different spindle lengths for double and triple. For example, Shimano used to make 109 mm long BB's for double cranks and 118 mm long BB's for triples. This allows to move the outer ring of the triple further away from the frame, to make room for the third ring.

If you took the original double crank off and put a triple in its place without swapping the BB, the inner ring will end up too close to the frame and shifting won't work. That's exactly what you describe.
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Old 10-23-13, 08:23 PM
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I think you nailed it hamster and CAC. I'm gonna measure the existing BB tomorrow and see if I can get a longer one.

Thanks All
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