Sunday, July 19, 2015

Difference between Ultegra 6770 Di2 and Ultegra 6870 Di2

Now that all the top end groupsets are moving towards 11 speeds, Shimano Di2 components have also been upgraded from 10 to 11 speeds. For Ultegra Di2, it has changed from the first generation 10 speed Ultegra 6770 to the latest generation of 11 speed Ultegra Di2 6870. On the Dahon Boardwalk, I have also installed Ultegra Di2 6870.

This new generation of Ultegra 6870 Di2 has been refined and improved from the previous generation of Di2 components. The main differences are in the rear derailleur and front derailleur, with only minor changes to the shifters. Let's take a closer look at the old and new Ultegra Di2 RD and FD, and see the differences and similarities.

New Ultegra Di2 6870 FD, 138 grams

 Old Ultegra Di2 6770 FD, 167 grams. Heavier by almost 30 grams.

Old FD on the left, new FD on the right. The new FD is much smaller in size!

The difference in size of the servo motor, as seen by the size of the casing

New FD is shorter and more compact

Comparing the size from the rear

Another picture comparing the size of the servo motor. This new Ultegra Di2 FD is similar in size to the Dura-Ace Di2 FD.

Some hollow rivets are used for the new FD as shown on the right side

Wire connection port on the new FD is located at a more hidden location

See the difference in the wire routing. Wire for the new FD exits at the rear, which makes it neater than the old FD.

The major difference for the Ultegra Di2 FD would be the size of the FD. This new generation of Ultegra 6870 Di2 FD is much smaller in size than the previous generation. Now, the Ultegra Di2 FD is similar in size to the Dura-Ace FD, which is great.

Another difference is the wire routing, which is neater on the new FD, as it exits at the rear-bottom, and can be well hidden by the frame. Other than these differences, the other parts of the new FD look similar to the old design.

Next, we will compare the old Ultegra Di2 6770 10 speed RD to the new Ultegra Di2 6870 11 speed RD.

New Ultegra Di2 6870 11 speed RD, 256 grams

Old Ultegra Di2 6770 10 speed RD, 272 grams.

Obvious difference in size between the new RD on the left and the old RD on the right

The servo motor on the old RD is much larger than on the new RD!

The old RD sticks out a lot more than the new RD

The limit screws have been moved from the bottom to the top of the RD 

The linkages have been changed, with the crash protection arm located at the bottom of the new RD instead of at the top for the old RD

Close up look at the crash protection arm on the new RD

For the old RD, the limit screws are located at the bottom, together with the stopper plate of the RD. 

Similar to the FD, the main difference for the RD would be the size. As seen from the pictures above, the new RD is much smaller in size than the old RD. In fact, it is similar in size to the new Dura-Ace Di2 9070 RD. All other parts look quite similar, and the wire connection port is also located at the same area on top.

In summary, for this new generation of Ultegra Di2 6870 RD and FD, the component sizes have been greatly reduced compared to the previous 6770 generation. The sizes are now very similar to the Dura-Ace Di2 9070 components, which is really good. This makes the Ultegra Di2 components a very good deal, as the performance and size is similar to Dura-Ace, and yet is available at half the price of Dura-Ace.


  1. Hi Steve, thanks for the informative postings. I am currently a newbie and interested in getting a foldable bike. I have shortlisted to this two bikes and would like to have more advice on which is more value for money as well as easier future upgrading. Thanks.

    Java Fit 16s-d ($788)
    Crank SOLTD-321 42*52T*165
    Cassette - PG830-11-30T
    Weight 12.4kg
    Seatpost - 33.9* 550
    Handlebar -28.6* 25.4
    Bottom Bracket - Neco B910 68MM*122.5MM
    Rim - WTB DX17 20*1.5*24H
    Inner Tube - CST Speedway 20* 1.35
    Tire - CST 20* 1.25/15A/V
    Gear Shifter - Shimano ST-EF51
    Front Derailleur - Shimano FD-2300
    Rear Derailleur - Shimano RD-M310
    Disk - HS1 160
    Disc Brake - AVID BB5

    Crius Velocity II 9 Speed ($895)
    Frame CRIUS Velocity - Aluminium 6061
    Crank Litepro 130mm 52t
    Cassette SunRace 11t-32t
    Weight Approximately 10.1kg
    Seatpost 33.9* 550 A62
    Handlebar 28.6* 25.4
    Cable Jagwire
    Pedals Litepro m258
    Rim Litepro K-fun 20inch 406-V
    Inner Tube Kenda 20 X 1.25 - 1.5
    Tire Schwalbe Kojak 20 X 1.3
    Gear Shifter Shimano SL m4000 R / Shimano SL m4000 L
    Brake Levers Avid FR5
    Front / rear brakes Avid SINGLE DIGIT
    Rear Derailleur Shimano Sora 3500


  2. I would recommend the Crius as it has better components and more lightweight. Also, it is similar to a Dahon so you can upgrade other components such as the handlepost.

  3. May I know if the electronic shifter is a worthy upgrade from mechanical shifter?I'm a bit skeptical about their firmware ( I work in IT industry ) and also we observe at least 1 bug 9 months ago in their mobile apps and they have not release any fix yet.

    1. The shifting is flawless and effortless compared to mechanical shifting. You need to try it to understand how good it is.
      I have not had a problem with the firmware at all. What is the bug that you encountered, and in what mobile app?

  4. Sorry bro, I mixed up with Garmin connect mobile apps.
    Thank for the feedback on Di2, that would be my next upgrade.

  5. Hello Steve this publication have too many time ago. But I have a question pls. I smashed my RD Ultigra 6770 today. As you know this is 10 speed. I purchased the bike in second half 2013 or in first half 2014 really I don´t remember. So since I can no longer find 6770, can I use a 6870 for 10 speed. If I buy RD I need to buy a chain too, I have a cassette with 11sp.

    - Would I also need a firmware upgrade if I'm using it as 10 or 11 speed or not really?

    - would I need to replace the cassette to 11 also the chain? again I just want to use 10 speed but if the 6870 give a possibility to mix with all other components from 6770.


  6. You can't mix 6770 with 6870, except the shifters. You can either find a 6770 to match your current system, or get 6870 groupset to change all to 11 speed.
    Are you based in Singapore? If yes, I have a used 6770 rd that I can let go for a good price.