Originally Posted by
Jeff Wills
Yes. The lever arm (the one the cable bolts to) is longer from the pivot to the bolt. This gives it more leverage on the cage (for shifts under pressure) but moves the cage less for each millimeter of pull on the cable.
I've run into this problem dozens of times- three times on my own bikes. The only good solution is getting the correct front derailleur.
Really?
When I switched from a Shimano FD-R443 road front derailleur to a Shimano Deore FD-M531 mountain front derailleur, I used the same shifters and experienced no problems.
When I read your reply, I got out my calipers and measured my two derailleurs (road vs mountain) from the pivot point to where the cable pulls on the lever and found them to be exactly the same.
Perhaps, there are derailleurs with different lever arm lengths.
However, from my limited experience with road and mountain derailleurs, I see no difference in the lever arm length.
Also, think about all the recumbent riders who have gotten rid of their road cranksets and replaced them with mountain cranksets to provide lower gearing.
Most of them have also replaced their front derailleurs from road to mountain.
I don't remember any posts discussing problems when switching to mountain derailleurs and using their existing shifters.