gearing - can 32t cog fit on Ultegra 6700 RD

[tharmor]

I'm currently running 2009 Ultegra 6700 FD & RD, with an 11-25 rear cassette. This gearing was rarely ever a problem for me when I was riding in California (at sea level). Now I'm living in Salt Lake City Utah and every ride contains some form of steep climbing.

Here's my question ::

In order to achieve a lower gear, how big can I go in the low gear without buying a new RD? (I was told it maxes out at 27t)

And, if I want to go up to 32t, which RD model will work with my current setup? (Again, I was told the Ultegra 6700a short cage would work)

Of note - my setup is 10speed.

Any advice would be greatly appreciated. I'm looking for the wisdom if the weightweenies to prevent me from making a poor choice here.

Cheers!!

[jipperd]

You can easily use a 28 or 29 without a problem. A 30T can use but will depend on your frameset. 30+ can be used but you'll need a 'long cage' derailleur like triple derailleur.

[tharmor]

I've investigated further and it would appear that with a long cage 10 speed rear derailleur I can go up to a 12-30 cassette. That's doable.

[efeballi]

Chain length can be an issue. You may run out of chain slack in the big-big combo if the chain isn't long enough.


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[bombertodd]

I've investigated further and it would appear that with a long cage 10 speed rear derailleur I can go up to a 12-30 cassette. That's doable.

I would think you can go bigger than a 30 tooth. My wife had a 12-30 cassette on her 6700 drive train. She was running the short cage (standard) derailleur too. You might try buying the cassette and see if it fits before purchasing the long cage derailleur.

[tharmor]

Now I'm actually wondering how I would even know which 6700 RD I have, since it doesn't say anywhere. Is it obvious?




ipad photo fail FTW.

[bombertodd]

That is a regular (short cage) derailleur. Easiest way to tell is the pulleys are closer together. I'm not sure if there are any specific markings between the two.

[tharmor]

@bombertodd - thanks for the info. Now the new questions becomes - How big can I go on a 6700 short cage derailleur (10 speed)? And are there specific guarantees from Shimano on the matter?

I need to start sorting fact from hearsay.

[eric]

I think 6700 is spec'd at 27t max cog. You can almost for sure go to 30t. It depends on how long your derailleur hanger is. Shimano publishes standards for the hanger but the bike makers ignore them. Shimano will only guarantee what they spec but their spec is conservative so they can guarantee it. The spec for chain wrap is the same. I have been able to push both the wrap and largest cog 2-3t past the spec as have many other people.

I have used 30t cogs on 7800, 7900 and 2012 Red derailleurs, with 50/34 chainrings, on Cervelo R3s. I use that for extreme climbing races. 32t probably won't work for you. It didn't with my red derailleur.

You can also get lower gearing by using a 110mm BCD crank with a 34t small ring if you're not already. A 33t ring will fit many cranks. You can get them from Harris Cyclery.

Shimano makes a 12-30 cassette.

Your derailleur is a standard road short cage.

You may need a longer chain with that 30t cog, and may need to adjust the B screw.

[tharmor]

@eric - dear lord, thank you! At one point while reading your post I thought for sure I had started to read another language. I had to reread it a few times to wrap my mind around it.

Thanks nonetheless.

I have a 2009 Cervelo RS. Is there a way for me to check out the manufacturer's spec on the matter?

[deltree]

Now I'm actually wondering how I would even know which 6700 RD I have, since it doesn't say anywhere. Is it obvious?




ipad photo fail FTW.

Ummm, am I going insane, this is a 6600 RD no?

[tharmor]

@deltree - I think you just saved me from making a huge mistake. Thanks! You are correct. I was assuming (ass!) that since it was an '09 that it was 6700. By looking up some pictures on the internet, I definitely have Ultegra 6600 SL.

Well, this thread has been sufficiently effed up by my huge oversight.

Now I'm left wondering if I can still go with a 12-30 cassette with the 6600 SL rear derailleur.

Thanks for all your help.

[eric]

I have a 2009 Cervelo RS. Is there a way for me to check out the manufacturer's spec on the matter?

Not that I know of. But 30t works for other people with Cervelos.

[tharmor]

According to the product listing on wiggle.co the 6600 SL can accommodate up to 27t ::

"Much has been written and reported on the sexier, more visible components like cranks and wheels, but as many have experienced, the drivetrain's the thing, and a reliable, durable and quiet rear derailleur plays an important role. Shimano's Ultegra SL rear mech ranges comfortably between 11 and 27 teeth cogs, and the short cage that I tested worked right our of the box. The set screws were easily accesible and smooth to turn, while the threaded boss attached to the deraiileur hanger as expected, a credit to Shimano's forging mastery and command of aluminium."

Again, according to what you all are telling me, this is just a conservative figure, and I should be paying more attention to Cervelo's accommodations with the derailleur's hanger.

[eric]

Many other people have done it (30t). I've done it on my Cervelo R3s (2006 R3, 2009 R3SL) which use the same hanger, with 7703 and 7900 derailleurs.
The 7703 is specd for 27t, the 7900 for 28t. Both handled the 30t without even touching the B screw.

If it doesn't work (but it will) you could get a 6700-A. That's spec'd for 30t. Or you could get the 6700-A and a 32t cog.