my name is Jim
Join Date: Aug 2010
Location: Park City, Utah
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Dura Ace 7900 FD adjustment
Having problem getting DA 7900 FD adjusted to my satisfaction. I am fairly knowledgeable and have adjusted FD many times before successfully. This is a new install of a full DA 7900 group on a Giant Defy Advanced frame. Frame had FSA BB86 bottom bracket in place already so I used it. It is supposed to be completely compatible with Shimano Hollowtech II cranks and I had no problems with the install or function.
The symptoms are an inability to get a combination of high stop setting and cable tension which both avoids overshifting and dropping the chain to the outside and has reasonable lever effort. If I set the high stop to avoid overshift it is very hard to get the lever to click into the high position. The lever high position stop puts the FD so close to its high stop that you have to really mash the lever and stretch the cable to get it to click into position. And I have to set cable tension really loose to even get it to click in at all. In effect either the stop in the brifter is too far out or the chainrings are too far in.
I can find no way to adjust the stop in the brifter. So my solutions are to live with it or to install a small (1-2mm) spacer on the drive side of the crank to move it out a bit. I know Giant sells this frame with the DA7900 group exactly like I have. I know they use the Shimano BB instead of the FSA but they should be the same. I don't know if Giant uses a spacer or not. I can get it to work but the lever effort is a bit much.
Any ideas? Is my spacer idea reasonable? I have checked and rechecked everything else.