Bicycle Mechanics - Ultegra 6700 rear derailleur w/ 6600 shifters?

I'm building a commuter bike and have Ultegra 6600 shifters, front derailleur and crank. If I use a 6700 rear derailleur, is it going to reduce the drive train performance in any way compared to finding the matching 6600 rear derailleur?

Shimano puts a scary-sounding disclaimer on the 6700 spec that suggests you need to use other 6700 shifters and parts. Is that just marketing hype to get you to buy everything again, or is there anything to that?

AFAIK, there is no change to the RD's actuation ratio, so it should work.

No problem. See this link http://cycle.shimano-eu.com/publish/content/global_cycle/en/nl/index/tech_support/faq_s/compatibility.download.-Par70parsys-0024-downloadFile.html/Road_charts_2009.pdf

Agreed, you can swap those around and it should make no difference.

This will NOT be an issue in ANY respect. Multiple (DA 78xx,Ultegra,105) shifters have worked perfectly properly with the Ultegra 6700 in my personal experience. I am not a fan of 6700 aesthetics, but I swear the R Der is quieter than the 7800/6600... maybe my imagination, maybe a pulley design change, maybe just a byproduct of clean new builds with new chains. Both front and rear 6700 derailers are fine with all historical Shimano 10sp brifters, regardless of any lingering older "spend-more-please" Shimano incompatibility claims you may find. Mix as you like.

Shimano *LOVES* to scare it's customers into thinking that if a bolt falls off - you need to buy a new gruppo from them. You're gold.

Don't believe the hype.

Super, guys---thanks a lot for the clarification. And Panthers007, great photo!

Just to add to the good advice above. You could safely use any 10 speed Shimano derailleur without any real difference in performance. In fact, all but the very old rear derailleurs are compatible. My wife's bike is running a 10 speed chain on a 6 speed triple crank, with a double front derailleur, an 8 speed rear derailleur and a 9 speed cassette--no problems whatsoever. Bike companies want you to buy more stuff, but the only real compatibility issues are between the pull of the shifters and the swing (indexing) of the derailleurs. All modern Shimano derailleurs are compatible with all Shimano shifters.

If you're building a commuter, a Shimano Deore XT or Shimano 105 rear derailleur would be an excellent choice.

All modern Shimano derailleurs are compatible with all Shimano shifters.

Spoke too fast. The front derailleurs are better off being kept with the same speed as the chain, since they are optimized for the external width of the chain for the smoothest shifting. But you could still probably get away with mixing it up--certainly if you use friction shifting on the front.

So just to clarify here, I could get away with using my 9s Tiagra front derailleur with 6700 shifters/rear derailleur and a 10s chain and cassette?

I've been using a 7sp DA braze on derailer with a 9sp Sram chain, 9sp Shimano cassette, and 10sp ultegra rings up front with 9sp Ultegra sti shifters for 5 years with no problems. I did pinch the center of the cage in just a bit though.

Shimano puts a scary-sounding disclaimer on the 6700 spec that suggests you need to use other 6700 shifters and parts.

I thought there was a change made in the latest Dura-Ace and Ultegra groups that does require using the same model number front brifter and front derailer. But it does not apply to the rear.