How to Identify Shimano Di2 Generations

Types / Generations of Di2

Shimano’s Di2 systems are divided into compatibility groups based on the “master unit”, which manages the entire Di2 system.

The master unit is located in the battery (or battery mount)—not in the STI levers or derailleurs.

To date, Shimano has released three distinct Di2 generations:

• 7970 series
• BTR/DN100 series
• DN300 series

Shimano does not officially assign generation names, but for clarity, we’ll refer to these as Generation 0, 1, and 2 respectively.

DURA-ACE 7970 Generation

The first-ever Di2 system, DURA-ACE Di2 7970, is a unique setup and incompatible with all modern Di2 parts. Because it has no backward compatibility, we’ve labeled it as Generation 0.

The electric wires used in the 7970 generation are proprietary and not compatible with any other Di2 generation. You must use a full 7970 set for the system to function.

However, the battery unit SM-BTR1 and its charger can still be used with first-generation Di2 systems.

Di2 Generation 1 / BTR Series

First introduced with ULTEGRA Di2 6770, and continued through DURA-ACE Di2 9070 and ULTEGRA Di2 6870, this is commonly referred to as the BTR generation. The generation name comes from the battery model numbers (e.g., SM-BTR2).

• If you’re using an internal battery, the master unit is located inside the battery (SM-BTR2).
• If you’re using an external battery, the master unit is located in the battery mount (SM-BMR1 or SM-BMR2).

Compared to Generation 0, major improvements include:

1. Option for internal battery integration
2. Junction A/B separation, allowing more flexible wiring layouts
3. Support for ANT+ wireless units

The DURA-ACE Di2 R9150, released in 2016, marks the beginning of the DN100 generation (Gen 1.1), but it retains high compatibility with most Gen 1 (BTR) components.

However, there is a key difference in wireless communication:

• BTR generation supports ANT+ only
• DN100 generation supports Bluetooth LE, which is now the standard

So, if you want to use Bluetooth wireless units or a System Information Display, you’ll need to upgrade your master unit to the DN100 series.

Di2 Generation 1.1 / DN100 Series

The “Di2 DN100 series,” introduced with the DURA-ACE Di2 R9150, is a minor upgrade of the Di2 BTR generation. Since most components are compatible with the BTR series, it can be considered a refined version of the first generation.

The master unit is BT-DN110 for the internal battery type, and BM-DN100 for the external battery mount type. Both have model numbers starting with “DN,” making them easy to identify.

The main difference is support for wireless Bluetooth communication.

It’s unlikely that you would downgrade from the DN100 series to the BTR series, but if your setup includes a Bluetooth wireless system, make sure to always use DN100 series batteries when replacing them.

Additionally, the DN100 series master units are compatible with the previous generation BTR series wireless units (ANT+ only).

Di2 Generation 2 / DN300 Series

The second generation of Di2 is the “Di2 DN300 series.” The major advancement is the introduction of the semi-wireless system with DURA-ACE R9200 and ULTEGRA R8100 (rim brake models such as ST-R9200 and ST-R8100 remain wired).

In the DN300 generation, external batteries have been discontinued, and the internal battery “BT-DN300” is the only master unit. While it looks similar to BT-DN110, it has three SD ports, making it distinguishable by appearance.

In the semi-wireless system, only the battery/master unit and front/rear derailleurs are wired, while STI levers act as switches, powered by coin cell batteries.

With Bluetooth built into the rear derailleur, a separate wireless unit is no longer required.

In the Di2 DN300 series, battery charging is done via the connected rear derailleur using the dedicated EW-EC300 charger connector.

For rim brake models, a junction box (EW-JC304) is still needed to connect STI levers to the master unit, as in previous generations.

Di2 Generations by Component

Road Di2 Series

The road-oriented Di2 series includes the largest number of product lines and different levels of compatibility, so extra caution is needed when building a Di2 system.

As explained earlier, there are three major generations:

1. 7970 Generation
2. First Generation
3. Second Generation

The First Generation is particularly important to note. Compatibility can vary depending on whether a wireless unit is included. When purchasing a complete Di2-equipped bike or Di2 component set, be sure to check the included battery unit, as this affects the wireless functionality.

Additionally, when assembling a Di2 setup, whether it’s based on the BTR series or DN100 series will determine how the wireless unit is integrated. If you want Bluetooth connectivity, be sure to choose components from the DN100 series.

MTB Di2 Series

Shimano’s Di2 lineup for MTB currently includes only two 11-speed series from the first generation. While Shimano’s latest MTB components have moved to 12-speed systems, as of March 2024, no 12-speed MTB Di2 series has been released.