I’ve started a new project for which I’ll be needing a new rear derailleur. It’ll be a 1×10 speed conversion and my eye caught Shimano Dura-Ace RD-7900 rear derailleur.
The reason why I’m interested in the difference between Dura-Ace and Ultegra in general, and rear derailleurs in particular, is because this rear mech goes for 80 euros. That’s not exactly peanuts, especially considering I’ve already spent several hundreds of euros on other parts.
I’ve researched hundreds of products and know for a fact that the difference between XTR and Deore XT clipless pedals is virtually non-existent. So why would Dura-Ace and Ultegra rear derailleurs be any different?
That’s what we’re going to find out.
Current rear derailleurs I own and have ridden
I already own a lot of bikes with a lot of Shimano groupsets. Two in fact are with Shimano Dura-Ace rear mechs. A Dura-Ace EX from 1979 and Dura-Ace RD-7700 from 1997. The first one is 6-speed and the latter 9-speed.
The others are mountain bikes with mostly Deore XT. Some when Deore XT was the most expensive groupset there was because XTR didn’t exist yet. Here’s the full list:
Koga Miyata Gent’s Luxe-S
Shimano Dura-Ace Ex
Koga Miyata Adventure
Shimano 600 SIS RD-6208
Koga Miyate Skyrunner Carbolite
Shimano Deore XT RD-M735
Cannondale Super V
Shimano Deore XT RD-739
Trek MountainTrack 800
Shimano Altus RD-CT92
Imperial Cycles Jaguar
Shimano SIS RD-TY20
Shimano STX RD-MC34
Scott Town XC
Shimano 200GS RD-M200
Cannondale Killer V
Shimano Dura-Ace RD-7700
Koga Miyata Roadwinner
Shimano 105 RD-5501
As you can see I’ve run the gamut of Shimano rear derailleurs, all the way from the cheapest Altus and 200GS groupset to the most expensive Dura-Ace.
Functionality of Dura-Ace versus Ultegra
With new chains and cassettes I found that non of the issues I had to deal with were related to the quality of the rear derailleur. They were either compatibility issues or worn cassettes that needed replacement.
So basically the Shimano Altus derailleur performed just as good as the Dura-Ace version. So with this very non-scientific experiment out of the way, my conclusion is that the difference between Dura-Ace and Ultegra rear derailleurs from a functional standpoint is basically non-existent.
If I can’t feel it with anything lower quality than Ultegra, why would I feel the difference with Ultegra?
Difference between Shimano Dura-Ace RD-7900 and Shimano Ultegra RD-6700 rear derailleurs
The Ultegra closest to the Dura-Ace RD-7900 is the Ultegra RD-6700, which came out a year later in 2009. Let’s take a look at a couple of specifications.
jockey wheel bearing
front plate pivot body
To be fair, I was unable to look up the exact specifications of the Ultegra rear derailleur, but based on personal experience with other derailleurs and how brands spec their products I made educated guesses. The prices are current prices found online.
If my assumptions about the Ultegra derailleur are correct, you will not get any noticeable gains by having a ceramic bearing, titanium pivot bolt or carbon alloy derailleur body.
If there are any marginal gains, they might be because carbon is almost twice as stiff as aluminum. The same probably goes for the thermoplastic front plate, although I don’t have exact numbers on how much stiffer it might be.
Besides the obvious gain in lowering the derailleur weight, the increased stiffness results in a crispier, more accurate shifting experience. How much better I cannot say, because I lack the exact numbers.
The gains are probably not worth the fact that the Dura-Ace is twice as expensive as the Ultegra. You can fairly assume the derailleur will not shift twice as well.
Johan van Seijen is the founder of restoration.bike. His cycling career has seen him at the starting line of classics such as the Amstel Gold Race and Liege Bastogne Liege. Realizing his racing capacity would fall short of what was needed he obtained a MS from the University of Amsterdam in engineering. His love for cycling changed into riding in an amateur capacity with his local cycling club TFC Weesp as a roadie and supporting MTB Noordwest as a mountain biker. He repairs, restores, and builds bicycles and shares his knowledge on YouTube, Facebook and this website.