70sSanO

I understand wanting keep an Ultegra group intact and for your setup it will work great. The 9 speed MTB “rear” detailleur is with a 10 speed cassette and 10 speed (road) brifters. At one time that was a preferred setup using 10 speed cassette and 10 speed (road) brifters for cyclocross. There are a bunch of threads out there.

I only brought it up because you started talking about using a wolf tooth at some point in time. You can live by the tech docs; but I would think looking at people who are playing in the mud in the real world carries at lot more weight.

John

Edit Added: The truth is, your hanger has as much to do with pushing max cog as anything else... up to a point.

Bill Kapaun

Actually, the "stack" of a 9 speed is slightly wider than 10. Slightly thicker cogs & spacers.
You install a 1.8?mm spacer on the FH body when using a 10 speed cassette vs 8 or 9.
Both RDER's have the same cable actuation ratio. A 10 speed just pulls slightly less per shift. The "brains" is in the shifter. The RDER is just a slave.

When you count your "steps", you have to remember you're already standing on the 1st one.

Davet

Barry2: the bolded quote is the key to understanding what is being said about the use of 9-speed MTB rear derailleurs with 10-shifters. The ‘pull ratio’ of both is the same, so when the shifter tells the derailleur to move “just this much” it does.

I know you’re going to go in a different direction but I’m posting this as an FYI hoping you can wrap your head around why 9-speed can be happy with 10-speed. Back when 10-speed was new there were no large cassettes that the touring community could use. When it was found that 9-speed rear ders worked perfectly it became very common to use that combination.

Barry2 

DaveT,
Thank you for the clarification.
So 9sp RD moves the same distance regardless of 9sp or 10sp brifter. The 10sp brifter simply moves less per step.
Got it.

Barry

tFUnK

OP I'm glad you've finally settled on a setup that works.

But my goodness how many times does one need to be told that 1) the original 6700 RD would have worked fine with a 30t (and in many cases 32t) cassette and 2) the best way to go beyond a 32t cassette is to use a Shimano MTB 9sp RD?

Barry2 

tFUnk,
About the same number of times you need to be told it was about the WHY and learning something.

Davet

¡Perfecto!

tFUnK

Fair. We're all just trying to help you avoid panic-buying extra cassettes derailleurs.

Barry2 

You say that like its a bad thing

My wife keeps me in a lifestyle to which I've become accustomed!

ne46st

I've been using RD-5700 GS / RD-6700 GS with SRAM 1070 32t cassette for years. With SS I can go up to 30t no problem. If I remember right, when I did a similar research some time ago, someone explained the reason why Shimano only spec'd up to 30t cog is because that was (or is) their largest 10 speed road cassette at that time.

Barry2 

ne46st
Welcome to Bike Forums.
Just to let you know, you just woke up an extremely old thread (almost 2 years old).
It's not a problem for me, but some do frown upon it.

I finally wound up with an RD8000 series long cage (GS version) and a PC1170 SRAM 11-36 cassette.
It works great and details can be found in another of my threads.

All the best

Barry

70sSanO

It is funny, but the last 2 years of aging have really changed my perspective of a 2t cog change. In years past that would have been fine, but at a certain point going from 28t to 30t isn’t significant enough.

Going to 36t is probably a better long term move.

John

Barry2 

70sSanO John,
At 58yrs I find a 11-36 very helpful. Despite the abuse I receive from a certain "friend".
And yes, if I had his FTP (approaching double mine) then I wouldn't need 11-36 either!

If you like to see what I did..... HERE
It's way beyond Shimano specs, but I've been running it for 8 months & ~3000 miles without issue.
Even had a buddy go the same route with a mechanical (non Di2) R8000-GS long cage.
Just be really sure to get the chain length correct. I recommend the Park Tool Video (Big-Big+2) method.



Barry

tFUnK

Two years later and I, too, chuckle at how much thought we've put into the 30t/32t discussion. I'm on the same boat now: currently running a 13-40t (custom/mismatched) cassette on a SRAM Rival WiFli with an extender on the gravel setup.

ganner

I bought a BNIB 6700 RD but realized I want the silver colour instead. Up for grabs, it was costly. Letting go 170$ if anyone interested.

Fidler

I am in the market for a BNIB RD-6700A-GS

Please let me know if you see one.