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Old 04-03-08, 04:26 PM   #1
Doolittle
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Trouble Downshifting with STI-Triple

So in 2005, I got a good deal on a Lemond Versailles with an 9 speed Ultegra rear derailleur, and 105 everything else, except for a Bontrager triple crank. I never really use the granny ring, but I got a really good deal on the bike and the 30 grams it adds didn't trouble me much. I cracked that frame in a fall due to streetcar tracks (don't cross them at over 30 k/hr). I then got a 2007 Lemond Buenos Aires frame at cost and swapped all the parts over. I've always had trouble with the front derailleur (if I had the money, my solution would be to upgrade to an Ultegra double), but now the shifting into the middle ring is worse than ever.

If I would like to downshift from the big ring to the middle, the derailleur just moves over a little bit while the chain stays on the big ring. Shift again and I drop down to the granny ring. I've tried tightening and loosening the cable a little bit and fiddled around with the barrel adjusters, but to no avail. At the moment, I'm inclined to take the new derailleur route (http://www.jensonusa.com/store/produ...erailleur.aspx). Any suggestions?
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Old 04-03-08, 04:42 PM   #2
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ive had this problem with many customers bikes and what normally solves that problem is to take tension off the front derailluer and loosen the clamp then pivot the derailluer in maybe 3 degrees. in as in the back part goes toward the frame.
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Old 04-03-08, 06:36 PM   #3
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Yeah, it sounds like the front shift cable may have too much tension.
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Old 04-03-08, 06:49 PM   #4
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Let some oil get into the cable housings once in a while, too, so the cables move freely.
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Old 04-03-08, 07:28 PM   #5
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Let some oil get into the cable housings once in a while, too, so the cables move freely.
Or new cables and housings could help.
Shooting WD40 into the shifters may help.
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Old 04-03-08, 08:00 PM   #6
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Originally Posted by Doolittle View Post
If I would like to downshift from the big ring to the middle, the derailleur just moves over a little bit while the chain stays on the big ring. Shift again and I drop down to the granny ring. I've tried tightening and loosening the cable a little bit and fiddled around with the barrel adjusters, but to no avail.
This might be your problem... Make sure the cable tension is correct and that the chain's position on the crank matches the positions on the shifter. My 105 10-speed front shifter has 6 positions: inner, trim1, middle, trim2, outer, trim3. (I don't know if the 105 front shifter of the 9-speed generation had all those trims.)

It's possible that the cable tension is so high that when the chain is on the outer ring, the shifter is actually in trim2 or maybe even the middle position. I've had it set up like this before and I could upshift through the chainrings just fine but when downshifting it would bypass the middle chainring.
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Old 04-04-08, 12:28 PM   #7
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The shifter needs to be in its lowest position with all of the cable out when the cable is attached to the derailleur. Flip the smaller shift lever several times and pull the slack out of the cable before attaching.

Al
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Old 04-04-08, 02:24 PM   #8
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So I seemed to have solved the problem by slightly decreasing the cable tension. However, I can only shift into the middle ring with the cable tension at a very specific point. Now the chain is rubbing on the outside ring and the limit screw doesn't seem to move the cage over enough to stop the rub. Increasing the cable tension to move the derailleur over means that the middle ring is then skipped. I'm at somewhat of a loss at the moment.

Je n'aime pas les derailleurs.
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Old 04-04-08, 02:41 PM   #9
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With the chain on the granny ring and the largest cassette cog and the cable released to the lowest shift position there should only be about 2mm of clearance between the chain and the inside derailleur rail. It's best to set the low limit screw with a relaxed or loose cable. Then take all of the slack out of the cable, attach to the derailleur making sure the cable is properly routed. After attaching the cable try adding some tension with the barrel adjustor, maybe a half turn counter clockwise. You should then be able to shift to the middle ring with one sweep of the brake lever/shifter (two full clicks, but don't count clicks, just shove). From the middle ring to the big ring should be one quick shove (one click).

Al
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