Bicycle Mechanics - DuraAce shift lever hangs up when shifting down to small chain ring
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12-25-10, 06:31 PM
Hi all, this is my first post and I'm hoping someone else has encountered this problem and can help me out. My road bike is equipped with DuraAce 9-speed. The problem, which I've been having for quite a while, is that the left STI shifter (brake handle) hangs up and doesn't want to slide sideways to allow a shift up to the big ring. Never a problem shifting down to the small, only up. To make the up-shift I always have to "play" around with it, which you can imagine gets pretty frustrating when you need the shift. The other oddity is that once I've freed it up, it shifts both down and up without a problem for a short time. But after I ride on the small ring for a while it's again hung up when I try to shift up.
Has anybody had this problem or have one of you expert mechanics run into this before? I could be wrong but the problem appears to be with the shift lever or maybe the cables, not the front derailleur, which seems to be fine when I loosen the cables and move it by hand. Please tell me I don't need to chunk out $400+ for a new set of STI shifters. Thanks for any help you can give me!
12-25-10, 06:35 PM
Whoops--got it wrong in the title; should read "DuraAce shift lever hangs up when shifting up to the large chain ring". Sorry for the confusion!!
12-25-10, 06:55 PM
worn out. no parts for the shift mech and no one is going to pay a mechanic to clean/rebuild it with no guarantee that it will help or fix it. only thing i can say is flood it with solvent and work the shifter. re oil with light oil
I doubt very much that it's worn out. The right one should wear out first, but it's common for the left one to display these symptoms first...
STIs depend on a number of tiny pawls that are quite lightly sprung. Over time the factory grease can become gungy and cause these little pivots to stick, making the lever behave exactly as you describe. If it was actually broken, it most likely wouldn't work at all.
I'd just give em a solvent bath. If that doesn't fix it, some ultrasound may be called for. It is possible to rebuild STIs, but it verges on watchmaking (http://www.bikeforums.net/showthread.php/610670-8spd-Ultegra-STI-shifter-%28original-style%29-rebuild-guide?p=10180619#post10180619).
Then once they were fixed, I'd sell em and go Shimergo for the win.
Try flushing out the shifters with WD 40. Use the aerosol can with the red straw and simply shoot lots of WD 40 directly into the shifter mechanism. This often restores STI shifting performance. The WD 40 acts as a solvent and cleaner to soften the factory grease and clean out dirt and general crud. WD 40 fixed my 9-speed Dura-Ace.
I second the motion to hose em out with WD40. As you're doing it, operate the shifter to help work in the WD40 and break up old stiff lube.
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