Bicycle Mechanics - Ultegra 6500 vs. Ultegra 6600 RD

Shifting with 9-speed STI units, is there any reason not to use the 6500 Ultegra FD, as opposed to the 6600? Ad for 6500 says "The FD-6500 Ultegra front derailleur features an extra wide cage to increase strength and extends service life. Indexed for light-action SIS shifting. 9 speed compatible."

Thanks.

FD or RD?

RD, doesn't really matter

FD, it's best if you stick to the same speed the chain is, since a 9sp chain is more likely to rub on a 10sp FD, and a 10sp chain will have sloppier shifting on a 9sp FD.

mind you, you can totally get away with mixing 9sp and 10sp FD/chain without a huge issue.

For all intents & purpose, I can't find any real difference between the RD 6500 and RD 6600 rear-derailleurs. I've had both and they shift like a dream.

Here's the bargain to end-all bargains. An RD 6500 for under $40 - brand-new:

http://www.cambriabike.com/shopexd.asp?id=68265&page=SHIMANO+ULTEGRA+RD-6500+REAR+DERAILLEUR

FD or RD?

RD, doesn't really matter

FD, it's best if you stick to the same speed the chain is, since a 9sp chain is more likely to rub on a 10sp FD, and a 10sp chain will have sloppier shifting on a 9sp FD.

mind you, you can totally get away with mixing 9sp and 10sp FD/chain without a huge issue.

Opps... Very Sorry... it is FD I am talking about. 6500 vs. 6600 front derailler. Am using 9-speed chain, brifters, etc.

it's best if you use a 9sp FD, 105 5500, ultegra 6500 or tiagra 4500, but it's not a big issue if you don't.

Are you talking about a front derailleur with a double crankset?
The 9-speed FD should work better with a 9-speed chain.
If triple you'll need the 6503.

Al

The FD 6503 can only be used on frames that run the cables underneath the bottom-bracket shell. It's a bottom-pull derailleur. If you have a Hybrid or a Mtn-Bike, you'll need something other than an Ultegra FD. One that is either top-pull of dual-pull.

Shifting with 9-speed STI units, is there any reason not to use the 6500 Ultegra FD, as opposed to the 6600? Ad for 6500 says "The FD-6500 Ultegra front derailleur features an extra wide cage to increase strength and extends service life. Indexed for light-action SIS shifting. 9 speed compatible."

Thanks.

I ran a 6600 with my 9 speed before going full 10 speed. With trim I wouldn't get any chain rub until the extreme crosses.

If you can get a 6500 you may as well, I got the 6600 because I was having trouble sourcing a 6500 and I knew I was going to be going full 10 in a few months.

I mix front derailleurs of all types. It doesn't seem to matter much. If it shifts and doesn't rub you're golden.