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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 09-20-10, 06:09 PM   #1
thehammerdog
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front Der just stopped working

I have a 2 yearold Bianci with 105 I went out for a ride went to shift down to small chain ring and it failed to move down, the shifting was working but it would not drop down.....as if the screw was adjusted....it was not. I looked at it, shifters worked, front der working moving but is will not shift down...................what could iti be. I hope to avoid a trip to the shop. FYI, the bike is left hanging between rides so it was untouched.
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Old 09-20-10, 06:42 PM   #2
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Check for a binding cable, either in the housing or under the bottom bracket.
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Old 09-20-10, 06:43 PM   #3
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Cable hung up on something?
You can test the derailleur by disconnecting the cable. This should allow the derailleur cage to quickly move all the way toward the seat tube. If it does, this means the problem is with the shifter or the cable.
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Old 09-21-10, 02:00 AM   #4
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Common problem with STIs... my old 8spd 600 ones did the same.

Caused by gummed-up grease (established by overhaul); you may be able to make it come good with a squirt of WD40 in the shifter.
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Old 09-21-10, 05:15 AM   #5
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Quote:
Originally Posted by waldowales View Post
Check for a binding cable, either in the housing or under the bottom bracket.
In addition to this if the cable frayed inside the brifter, where it wraps tightly around the drum, the shifting will be
buggered. Loosen the cable at the FD and push the cable out of the brifter a few inches, any fraying will be
obvious, in messy cases it will be really hard to get the cable out of the brifter.
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Old 09-21-10, 07:15 AM   #6
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thehammerdog, Reads like a integrated shifter is only triming, not shifting to it's home position. I've had two fail because the grease hardened preventing the shifter to fully home. Spraying WD40 or similar seems to work well on the FD shifter, much better than the RD shifter.

Brad
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Old 09-21-10, 12:06 PM   #7
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OK guys.......I went so far as to remove the cable it is a der issue...It just will not move down far enough to drop chain......I am afrais to undo the der as i have a carbon frame and I am fearfull to re attach and damage the frame as I cinch the4 bolt.....I never had a der just die....the bike is clean and well cared for......??????I dont know.
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Old 09-21-10, 02:01 PM   #8
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Drop the chain [screw at bottom of cage lets the chain come out, If the need be ]
and move the FD back and forth and feel if it's got resistance to going back and forth under the return spring power .



If you fear doing the repair, yourself, hire it out to the Bike shop (you Got it from).

Last edited by fietsbob; 09-21-10 at 02:05 PM.
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Old 09-21-10, 02:56 PM   #9
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I agree... if you are not comfortable doing the repair, but you do not want to go tot he shop... well, somethings gotta give.

Your options are:
Do the repair yourself and risk damaging the frame
Bring the bike to the shop
Do nothing and ride with one less chainring.

First thing I would check is the derailleur alignment... the edge of the outside of the FD cage should be 1- 2 mm above the big ring, and it must be perfectly parallel with the chainrings when viewed from above. If the derailleur was not properly secured then it may have shifted over time or gotten knocked out of place..
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Old 09-22-10, 02:17 PM   #10
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I've seen FDs seize up and not want to shift down, the fix was to apply lube to the pivots and manually move the FD back and forth a few times.
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Old 09-22-10, 04:03 PM   #11
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Is the front derailleur a clamp-on type? Most CF frames have braze-on front derailleurs. Either way, replacing is not rocket science.
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Old 09-22-10, 10:26 PM   #12
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...It just will not move down far enough to drop chain.......
Have you checked to make sure the lower limit screw is adjusted correctly?
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