Shimano Compatability

I've been told by Shimano reps that 5700 and 6700 front derailleurs are not compatible with older 5600 and 6600 levers. And vice-versa. The pull rates are different. But I never tried it, so I'm prepared to be told I'm full of [censored], or that I might get them to work together with some creative cable routing.

Also, triples require symmetric chains.

FWIW. My understanding is that oldbobcat is correct that the pull rate on the Shimano 5700 & 6700 front derailleurs is different than the pull rate on the Shimano 5600 & 6600 front derailleurs ...

It is also my understanding that the pull is MORE for the 5700 & 6700 front derailleurs ...

So, if THAT is correct, then you CAN use one of a 5600 series 105 shifter's 'extra' indexing indents which would typically be used to move the front derailleur's cage between the three chainrings of a Triple Crankset to move the 6700 front derailleur cage sufficiently between the inner & outer chainring on a Double Road Crankset ...

• as I have indicated in the past, I have successfully mated a 9-speed 105 shifter to an 8-speed XT (FD-739) front derailleur with a Double Road Crankset ... AFAIK, some 8-speed 105 shifters & all post-8-speed 105 shifters are Triple-capable (a good thing, IMO, because it allows some flexibility in mating Shimano shifters with unauthorized front derailleurs)
  

[*] I have also successfully mated a Campagnolo non-Chorus QS front shifter to a non-QS specific Campagnolo front derailleur with a Double Road Crankset