mcyak

I've got the older (pre 6700)6600 series ultegra 10 speed setup.
I'd like to change over from the 11-25 6600 series 10 cog setup currently on to the newer
6700 series 11-28.
I asked several LBS and got a "best we can offer is you'll have to try it" response
regarding the compatability of the 6600 series derailleur with the 28tooth cog.
Shimano listed 27t as the maximum cog the 6600 series could handle in the brochure
that came with the 2008 Motobecane IF bike.
Anyone tried the 11-28 with their older 6600 series ultegra derailleur?
If so, what was your experience?
Thanks

achoo

I've used 5600, 6700, 6600 and probably 7800 cassettes on Ultegra 6700 and DuraAce 7800 bikes. They all worked fine.

A 6700 cassette in a bike with a 6600 groupset should also be fine.

desertdork

Whether your RD6600 will accommodate a 28t cog will depend on the dimensions of your RD hanger. So, the responses you received from the LBS are correct.

brentley

it works fine. you do have to make sure the rear derailluer is properly adjusted for it.

HillRider

Good answer but it doesn't address the question. The OP was concerned whether a 28T large cog would work with his rear derailleur which is rated for 27T maximum.

Generally, yes it will work as many riders have reported being able to run 30T and even 32T large cogs with Shimano road rear derailleurs. However, since Shimano says 27T max., the LBS can't and won't guarantee the 28T cog will work. Smart money says it will.

scirocco

Just installed one myself with this exact combination. It's right on the limit of the 6600 RD and only just works and no more. I have to have the B screw wound right in to avoid the 28T cog from contacting the derailleur pulley. But once I did that it ran and shifted fine. As has been said, no guarantees on any given installation.

mcyak

A reputable local shop would be doing the set up.
My main concern covers the fact that shimano tweaked various items in their transition from the 6600 to the 6700 series (besides making items lighter)and in doing so may have created incompatability issues with older style ultegra.

"A deal is no deal if it don't work"

mcyak

Siroccos post addresses my fear.
The intent was to give the bike a bit more of a bail out gear riding the hill country in southwestern ny.
Pushing the gears (climbing) on an already 'tweaked to the limit' setting doesn't sound too good.
I may suck it up and have the LBS order an origional 6600 series 11-27 which should offer a bit more leeway.

mcyak

Thought I'd share the info and advice I've recieved (from Shimano )
While the 6700 11-28 is a issue with the 6600 derailleur, the 6700 derailleur isn't with the 6600 shifters (the indexing remained the same accd. to shimano)
Sooo..if you plunk down the extra coin (or get a bargin thru e-bay etc.)for the 6700 series cassette and derailleur you can use them with the 6600 shifters (color me happy)
To top that; "Dan" from shimanos technical devision (and his suggestion has been proved out by a local hill climber who runs this on his new CF Felt)informed me that the 105 series derailleur can accept up to a 32 tooth cog and easily run a 30 tooth and..it also works with the 6600 shifters. (color me happy again!)
In the hurray for me,bad for him department, a recent pileup on a local club ride resulted in several CF bikes being stripped for their parts.
I got my hands on a 'under 200 miles' 12-27 6600 cassette for..$35.
I'll see how the 127 works during the autumn and decide whether to 'downgrade' to the 105/5600(?)and the 12-30 10 speed cassette.
(what can I say..I spent a few weekends with the climbers and got hooked)