I have a bike with a standard 6600 triple group and 12-27 cassette. The cassette and chain are shot and I wondered if I could get away with putting the new 6700 11-28 cassette on.

Shimano specifies for the 6600-GS rear der a 27t max cog and total capacity of 37 that would be exceeded by 2 with 30-52 rings and 11-28 cassette. So it's not a supported config.

But 11-28 would be handy also for use on my other bike with 53/39 (e.g. at Battenkill next week) and Nashbar has it for a good price.

Does anyone have experience with this arrangement or can make a good guess?

My guess is that it will work but you'll likely need your b-screw turned all the way in (if it isn't already). You may even need a slightly longer screw to get clearance between the jockey wheel and large cog. When you size your chain, size it for the big/big combo and be willing to accept that the small/small might be unusable due to not enough derailler chain wrap capacity.

It will work, but of course you will need the 11t specific lockring.

Which will come with the 11-28 cassette. I have one sitting right here next to me waiting to go on a friend's bike (Dura Ace 7800 short cage rear derailler).

The difference is so minor that you'll have no problems whatsoever. Shimano's ratings are conservative, often very much so. I'll bet the new cassette will bolt on with no adjustments needed, B-tension or otherwise.

All Shimano and 11T Campy cassettes come with a new lockring included. The only cassettes not including the lockring are Campy 12T and larger cassette and they assume you use the locring that came with the hub.

Not entirely accurate. Super record cassettes come with lockrings 11t or 12t.

You do understand why that rating is set in stone right? It can go both ways, conservative, on the dot to less than official spec.

there are more than a few bicyclists running 11-32 with shimano road derailleurs but its not an officially sanctioned component combination.

you should give it a try and see how it goes for you.

I have it on my 9 speed.

alternately, put a shadow derailleur on there and be okeydokey to run up to 36 teeth in the back with impunity.

As far as I know, all Shimano MTB RDs are spec'd to a 34T max cog (but will like handle 36 as you say). There's no need to use the more expensive Shadow versions unless being low profile is a high priority.

It's only about $10 more. And I know I'm always hitting my (non-Shadow) derailers on stuff, knocking them out of alignment. I bought a DAG-2 to straighten hangers, but if one pays a shop for that sort of thing, the difference for the Shadow seems well worth it.

I've been really impressed with the Shadow. I have it on one of my bikes, and SRAM X-7 on another. The Shadow doesn't have a scratch while the SRAM looks like it's been mauled.

After reviewing prices again, my bias against the Shadow RDs is somewhat changed. When I was looking at them, I was only comparing an XTR 971 to an XTR 972 which have a retail price difference of over $80. Stepping down to XT brings about a much more reasonable price difference along the lines of what Mr. U has noted. I have heard that they are a little more finicky to set up and unless you often crash on the road, I still don't see much benefit in using one for that application. MTBing is a different story though.

A quick Google search found several 10-speed 12-27 cassettes available including the 6600. An 11-28 combined with a standard triple seems like overkill on both ends. Why not replace the 12-27 with another 12-27?

Well, Shimano has to take into account that their parts might be installed on a huge number of differently-configured frames. Their "spec" has to take into account the worst-case scenario- perhaps a vintage Rigi with 15" chainstays and a minimal distance between the axle and the derailleur mount, running the 12-27 cassette and 39-53 chainrings. (Never seen this- just sayin'.) In that case, the derailleur might have issues on a 28-tooth cog that it doesn't on a 27.

Since the OP's bike has Ultegra 6600 parts already, I'm betting that it's closer to the "ideal" dimensions than some whackdoodle vintage kitbashed bike. That's why I say switching from a 12-27 to a 11-28 won't be a problem.

oh, 2x10 and 11-36 10 speed is going to be next new 'hot' mountain gearing for mountain tourists and other people previously opting for the triple front crank.

not saying this is where the OP wants to take his bike, the 11-28 will work more than likely work fine for him. he should give it a try.

I put a 28 on my Shimano but you have to size the chain, your chain is probably going to be a link or two longer than your existing chain.

Like I said in the OP, cost is one reason: 11-28 is cheaper. The other is the 11-28 will be handy from time to time on my racing bike, which has a 53/39 crank.

Thanks for the comments, everyone. The cassette should arrive Weds. I'll see how it goes.

It works just fine. I use a CS-6700 11-28 with an Ultegra 6603 drive train. As others have stated, adjust the B-screw. In my case, the chain length was fine. The two effects of the 11-28 are I don't use the small chain ring nearly as much and I miss the 16T cog.

The 39/28 combo seems fine for most hills. The 30T chain ring is now truly a bail-out gear, analogous to 4L gear in a 4WD vehicle.

I prefer to have an single tooth jump from 15-16 instead of 15-17. So I took the 12-19 cogs from my 12-25 cassette and combined it with the 21-28 block to make a 12-28. It's perfect match for the t52/39/30 triple. I don't miss the 11T cog one bit. Funny thing is my new bike has 50/36 compact with 11-28 cassette and for some reason the missing 16T cog is not as noticeable as it was on my 52/39/30 triple.

on sat. i rode the 11-28 with 53/39 rings and a 1st gen. Force RD in Battenkill without adjusting chain length. it worked fine. (the low gear was just right for those hills.)

i'll move the cassette it onto the long-distance bike this week with a new chain.

the cassette works great with the 6600 triple and RD.

@fun2none : i have not been bother by the absence of the 16 on the road but it's a genuine problem on the trainer.