jvj

I have a bike with Ultegra 6600, compact crankset and a 11 (or 12) - 27 cassette.

If possibile I would like to get up to a 30 tooth max. I've been told than on 6600 (not 6700) that 27 is the most I can do.

Thank you for your help.

keisatsu

do you have a long or short cage RR Der?

guy2600

That's true if you stick with a road rear der (I think with a new road der you can get 28). If you put a mountain bike rear der. you can go to 36 depending..

rankin116

It doesn't have to be a mountain derailleur. If you get a long cage rear, it should be able to take up the chain slack from running such a wide range. Ultegra does offer a triple crankset, so I assume there is a long cage rear derailleur as well.

jvj

Thank you for your help.

scirocco

The derailleur size is the problem. There is not enough clearance between pulleys and ring to fit a 30 T ring even if one were available. You can just squeeze in a 28T but it's borderline and Shimano don't guarantee it. (You have to use a 6700 cassette, there's no such size in 6600).

And yes, you will need a long cage derailleur to avoid having the chain slack in some gears.

eofelis 

I have a bike with 6600 triple. I wanted much lower gears than a 27t cog in the back. I now have a 10sp 12-36 cassette and a 9sp XT Shadow rear der. (10sp rear der will not work for this.) It works great.

Barrettscv 

I'm running a Sram Apex 11-32 ten speed cassette with a Shimano Ultegra GS RD. Works perfectly.

See: https://www.bikeforums.net/showthread...-fear-no-hill?

fmcooper

I switched my RD from a 6600 to a 6700 and put on an 11-28 cassette, works like a champ. Did not make any other changes (cables, brifters, etc).

scirocco

Sure you're talking about an Ultegra 6600 RD? In that thread you quoted, you say that the RD is rated for 28T. The 6600 RD is not, it's only rated for 27T. The OP has 6600, not 6700.

I was using a 6600 RD with 28T for a while and it just, only just fitted with the B-screw wound all the way out to stop the pulleys hitting the ring. There is no way I could have got a larger ring on. But I guess it depends on the RD hanger length - if it's long enough you could get enough clearance I suppose.

eofelis 

Try this: take the rear derailleur off, remove the B screw, and reinstall the B screw from the other side. The result is that you effectively get a bit more B screw length by having the head of the B screw against the derailleur hanger. It might make the difference when trying to run a 28t cassette. Might even work well enough to allow the OP to use a 30t cassette. Worth a try anyway.

Right now I'm using this method on one of my bikes to make a 105 9spd rear derailleur work with a 12-32 cassette. It clears the 32t cassette and works fine. But there isn't enough room, though, for a 34t cassette.

It's been suggested to me that you could also just go down to the hardware store and get a longer screw of the same diameter and threading as a B screw. I haven't gone looking yet, so I don't know if a screw like this is something the neighborhood hardware store is likely to have.

Barrettscv 

Yes, I'm using a 6600 "GS" rear Derailer, see Sheldon Brown's explanation: https://sheldonbrown.com/gloss_ca-g.html#capacity

"Rear derailers are also commonly designed for a particular maximum size of rear sprocket. If you exceed this size by too much, the jockey pulley may rub against the sprocket when using the lowest gear.

Rated maximum rear sprocket size, however, is also commonly much lower than what actually works. For instance, Shimano's models designated as "road" derailers are generally listed for a "maximum" sprocket of 27 teeth...because 27 teeth is the largest size that they make in a designated "road" cassette. However, in almost all cases, these derailers, even the short-cage models, will handle rear sprockets as large as 30 teeth in practice. (This somewhat depends on the design of the frame's derailer hanger, so once in a while you will find a particular installation where you can't use a 30, but I've never seen one where a 28 wouldn't work.)

I'll also mention that many folks seem to be a bit mystified and intimidated by derailers. They're actually quite inexpensive and easy to replace, so it is foolish to allow the limitations of a particular derailer to keep you from having the gearing appropriate to your riding style/needs".

Steev

You could always try the larger cassette.
General opinion around the mechanics forum is that the max cog spec from Shimano is very conservative and often can be exceeded with good function. It depends on the geometry of the drop-out and derailleur hanger. If it doesn't clear, you'll have to get a derailleur with a larger max cog spec anyway so you won't be out anything to try.

I_like_cereal

Purchase a 28 tooth rear cog and install it with a spacer removing the lowest tooth cog. Adjust the Read D. If it works your only out $10. Or you could try it with a 30 and you'd be out the same.

I know that Sheldon's parent site has a 12/30 rear cog, but its pricey at over $100.

dwellman

True dat. So true. Stupid derailleur.

Barrettscv 

The last three cogs share a common carrier and are sold as a set. The Harris/Sheldon Brown 12/30 cassette is a nine speed.

IRD makes two 10-speed, Wide Range: 11-30, 12-30 cassettes worth considering: https://www.interlocracing.com/cassettes_steel.html

10-speed Elite Road Cassette:
Shimano 10 compatible version.
Nickel-chrome plated steel cogs with light alloy spiders. Save your precious titanium Dura-Ace sprocks for race day and use this on training rides. Even smarter. Use ours all the time.

Nickel Chrome plated cogs
Alloy spiders hold the 4 largest cogs.
Alloy and resin spacers
Shimano hub compatible
10-speed, Wide Range: 11-30, 12-30

clink83

Why bother making an improvised solution when an XTR derailler will give you the range you need, and still shift nice.

frperdurabo

And you've got 30 speeds, using your existing road bike brifter?

Thanks for your help - I'm a newb at this.