Shimano Di2 Update - Aug 2015
article by Andrew Strauss
images by N. Salazar, A. Strauss
Sep 5, 2015  hits 70,510

Di2: still the system to beat

It's no secret that at TriRig, we love Shimano's Di2 electronic group sets. Ever since we first wrote about Di2 back in 2011, we have sung its praises over and over again, and used it on numerous builds. But Di2 has been evolving. A lot has changed since the last time we wrote about it, and we thought it warranted a full article to discuss some of the changes and how they relate to triathletes.

The biggest change was the move from the initial 4 wire design of the first generation Dura-Ace 7970 system to the current 2-wire E-tube system. This system was used on the original Ultegra Di2 6770 group set, as well as the current Dura-Ace and Ultegra group sets (9070 and 6870 respectively). This change brought about new wires and connectors, which we will discuss in detail later on.

We also saw several other changes, including 11 speed drivetrains, more derailleur choices (short and mid cage), cassettes with larger ranges, better options for 1x setups (1 chain ring in front), some firmware issues, and a lot of choices for those who want electronic shifting at a lower price point.

While these changes are significant, the core feature set and performance that we fell in love with has remained largely unchanged, even with the lower cost components. Shifting is still the fastest and most precise we have ever seen from any group set. Auto-trimming reduces the possibility of change rub. Ergonomics are superb, and shifting forces are minimal. This means that you will most likely shift more often, which leads to a better ride experience.

Installation is also largely unchanged. You don't have to worry about bends or odd angles when routing your cables. Components are easy to disconnect and change when travelling. There is no cable tension or cable fraying to worry about, and you will never have a snapped shift cable. Derailleurs are easy to install and adjust through the micro-adjustment process. Working with Di2 is a pleasure.

Shift buttons can be customized any way you like, and base bar shifting continues to be one of our favorite features. Every time I ride a mechanical bike without the ability to shift from the base bar, I immediately notice, and long for Di2. This feature alone is enough to get me to use Di2.

So without further ado, let's examine what has changed it further detail on the next page...


  • The new E-Tube cables contain 2 wires instead of 4, have smaller cable and connector sizes, and have better waterproofing.
  • The small and sleek E-tube wire (left) versus the old 4-wire connector.
  • The small and sleek E-tube wire (top) versus the old 4-wire connector.
  • Shimano's 11-32 Cassette and Ultegra Di2 mid-cage rear derailleur (RD-6870-GS) are currently our favorite choices.
  • 11 speed Ultegra Di2 mid-cage rear derailleur (RD-6870-GS).
  • With a larger 32 tooth cassette like the 11-32 in this photo, you need a derailleur with a longer cage.  This allows the derailleur to take up the extra chain slack while you are in the smallest cog / chain ring, and keep your chain taught.  In this photo, we are in the largest cog and chainring, and you can see that the derailleur is at its loosest setting.
  • With a larger 32 tooth cassette like the 11-32 in this photo, you need a derailleur with a longer cage.  This allows the derailleur to take up the extra chain slack while you are in the smallest cog / chain ring, and keep your chain taught.  In this photo, we are in the smallest cog and chainring, and you can see that the derailleur is at its tightest setting.
  • Ultegra Di2 11-32 Cassette (CS-6800).  This is currently my favorite cassette, as it is very practical for climbing and 1x setups.
  • Ultegra Di2 front derailleur.
  • Ultegra Di2 front derailleur.
  • The smaller Ultegra 6770 front A junction (SM-EW67-A-E) is no longer compatible with 11 speed components and the SM-BTR2 internal battery.
  • The SM-BTR2 lipstick battery makes hiding the battery inside most seatposts easy.  Photo from Shimano.com
  • Comparison between a short-cage Dura-Ace Di2 derailleur (left) and the mid-cage Ultegra GS (right).
  • The new E-tube wiring is a very simple and efficient way to communicate shifting information and carry power across the system.
  • Shimano's bar-end shifters remain the industry's most ergonomic way to shift.
  • The brake-lever shifters, while adding some frontal area, provide the excellent feature of base bar shifting.

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