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Discussion Starter · #1 ·
I arrived in Italy to do some touring two weeks ago to find that my front derailleur (Shimano Tiagra Flightdeck, 3 front chain rings, on a Specialized Allez) would only shift to two of the rings, i.e. either the small and medium, or the medium and large chainrings. It worked fine before I disassembled the bike for shipping. The cable is brand new.

All adjustments of the cable tension, limit screws, derailleur angle didn't solve the problem. It seems like the shifter isn't providing enough of a range of tension. For instance, if I set it up so that it can shift between the small and medium chainring, up shifting does not pull the cable enough the get the derailleur to the large one. If I pull the cable itself with my hand, however, I can get it to move the large chain ring.

Any ideas about what the problem is?
 

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Did you detach the cable from the derailleur for shipping purposes? If so, it sounds like it was re-attached with way too little tension. Whenever I install front derailleurs I give the cable a pretty good pull (as in, what you would think is too much) before clamping it onto the derailleur.
 

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NeoRetroGrouch
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Is the cable routed correctly and attached to the correct side of the bolt?

Is the cable end set correctly in the slot in the shifter?

TF
 

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kfurrow said:
Did you detach the cable from the derailleur for shipping purposes? If so, it sounds like it was re-attached with way too little tension. Whenever I install front derailleurs I give the cable a pretty good pull (as in, what you would think is too much) before clamping it onto the derailleur.
Sorry but I don't agree. Before attaching the cable the shifter must be in the smallest ring if front or smallest cog if rear. If is important to work the small shift lever several times while pulling the free end of the cable. Then attach the cable to the derailleur with just enough tension to take up all of the slack. It may be necessary to make a tension adjustment after attaching but it should not need much adjusting.

Al
 

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Discussion Starter · #6 ·
Al1943 said:
Sorry but I don't agree. Before attaching the cable the shifter must be in the smallest ring if front or smallest cog if rear. If is important to work the small shift lever several times while pulling the free end of the cable. Then attach the cable to the derailleur with just enough tension to take up all of the slack. It may be necessary to make a tension adjustment after attaching but it should not need much adjusting.

Al
I did try detaching and reattaching the cable after all the the other adjustments failed. I followed the suggested procedure of putting the chain on the smallest ring, downshifting that the small-ring state, pulling the cable tight, and attaching it to the derailleur. In this case, the shifter doesn't pull the cable enough to move the derailleur to the big chain ring. If it increase the cable tension so that it does reach the big chain ring, then the shifter doesn't loosen the cable enough that the derailleur can reach the small chain ring.

My feeling is that either the shifter cannot vary the cable tension enough to make the system work, or the derailleur spring tension is too large so that a change in the cable tension isn't able to move it enough. Does anyone know how to change either the shifter travel or the front derailleur's spring tension?
 

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Discussion Starter · #7 ·
tornado said:
Other possibilities:

the cable's not connected to the der properly

the der got bent in shipping

the der isn't aligned properly

the cable isn't seated properly in either the shifter or the housing
I think I can rule out all the possibilities except the last, i.e. "the cable isn't seated properly in either the shifter or the housing".

How would I check this?
 

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Just to rule out another cause of sloppy or improper shifting, make sure the shifter cable runs cleanly through the bottom bracket guide. I had a cable once eat its way into the plastic guide instead of shifting my FD properly. It had jumped the guide channel when I fiddled with the FD.
 

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NeoRetroGrouch
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ec513 said:
How would I check these things? What is the correct configuration for these cases?
Look for the groove under the bolt to know where the cable goes.

Open up (apply the brake) the shifter and you can see the cable end. It should be down in the round slot.

TF
 
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