Hey gang, I have a 2009 Fuji Cross Comp that came with 5600 drivetrain with the exception of Ultegra RD. With the 5700 coming out with concealed cable routing, if I were to purchase and install the levers alone, is there any forseeable issue in swapping out my 5600 shifters?
I know that 6700 and 7900 have a different FD/crank that is slightly wider (just over 1mm I believe) that facilitates less rubbing when cross-chaining and also has a slightly longer cable pull on the derailleur. 5700 will probably inherit this.
As for the RD, I know that the 6700 will work with 6600 so I'm sure it will work the other way around. The cable pull never changed with Ultegra so I don't see why they would change it with 5700.
The cable pull thing made me drop a chain on a 6600 combo in the front on a couple occasions when I would quickly drop three toward the 11 in the rear and drop down to the small ring simultaneously. It was otherwise perfectly adjusted by myself the first two times and by my LBS (who confirmed I had it right by three techs) the third time it happened. This was all we could think of so if 5700 has the same design, you may want to rethink.
Well, I don't often drop three in the back at the same time as one in the front - that's crazy man! I called a LBS and got ahold of a tech I trust and he said that lever-only replacement is the way to go.
What about brake cable pull on the 5700? The 6700 and 7900 pull more brake cable than the 6600 and 7800 levers, but I have not yet heard whether this is also true for the new 5700 levers.
With the same hood design I suspect it would be the case. It's about lowering costs to manufacture. If SRAM and Campy have their top tiered kits using the exact shaped parts, the machining can be done by changing the material and not retooling. Same reason Shimano shifters were all the same for the 5600/6600/7800 generations. The machinery is the largest cost (and it's fixed no less) in manufacturing these things.