# Dura Ace RD 7700 functional range?



## Eiron (Sep 9, 2006)

Hi, I'm (finally) building up my randonneur & currently have an older XT short cage rear derailleur shifting perfectly on my 12-28 & 26/36/46 setup. This XT has 10t pulley wheels & the same link & cage lengths as the 105 RD of the same MY. The cage is stamped with 28 Max Capacity & (I think?) 28 Total Capacity.

A friend gave me a Dura Ace RD 7700 that I'd like to use on this drivetrain instead, but the Max/Total listed online for the derailleur is 27 Max & 29 Total. The link lengths appear to measure the same as the XT short cage, & the cage is maybe 2mm or 3mm shorter. This DA has 11t pulley wheels.

I've found numerous threads of folks using the DA RD 7700 on 13-30 cassettes, but with only double chainrings. Is anyone here using this RD on a triple? Or know what the outer limits of gear range is for it? And will the larger 11t pulleys give me comparable chain take-up to the slightly longer XT cage?

Thanks

Greg


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## Gnarly 928 (Nov 19, 2005)

I use these 7700 with a 34 chainring and a 27/11 cassette with no problems other than a bit of chain slap. For what that is worth.


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## |3iker (Jan 12, 2010)

I think you better do the good old chain capacity calculation.

(Large Ring - Small Ring) + (Large Cog - Small Cog) = Total Chain Capacity

I shall leave the joy or disappointment of the result to you.


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## Eiron (Sep 9, 2006)

Thanks Gnarly, I appreciate the info.

Thanks |3iker, that's why I'm asking for user experience: it differs from printed specs. I'm already operating outside the capacity of the XT. Just wondering about the DA now.


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## Kerry Irons (Feb 25, 2002)

*Work around*



Eiron said:


> Thanks Gnarly, I appreciate the info.
> 
> Thanks |3iker, that's why I'm asking for user experience: it differs from printed specs. I'm already operating outside the capacity of the XT. Just wondering about the DA now.


If you are willing to avoid the small chainring with the bottom half of the cassette, then you can run a regular road derailleur with a triple. You set things up as though it were a double (considering the middle ring and the large ring) and then only use the small chain ring with the 3-4 largest cassette cogs.


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## Eiron (Sep 9, 2006)

Just wanted to pass along this setup info for anyone interested:

I finally got a chance to install the DA RD-7700 on my 12-28 rear & 26/36/46 front setup. So far it's working better than the short cage XT RD-M735 SS I've been running.

On any of my bikes that I set up with a triple, I try not to run the small ring with the two smallest cogs or the large ring with the two largest cogs. So not having "full range" of all gears is not an issue for me. Since I plan on spending the majority of my riding time on this randonneur bike, I want the shifting to be as intuitive as possible. The DA 7700 seems to be the right direction for that goal.

So my next question is, does anyone know if I can use the XTR FD-M950 on my 26/36/46 ring combo? With the huge offset (drop?) between the front & back shift plates, it looks like it will hit the middle ring before completing the shift. I can't seem to find any good listing of ring range for this FD.

Thanks again,

Greg


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