12-speed Di2 New User Guide

If you've recently bought a new 12-speed Di2 bike - congratulations! I'm sure you have a lot of questions or are wondering how the nitty-gritty specifics of your bike work.

The supplied manuals usually aren't great, but don't worry - I'll walk you through the things you should absolutely know about 12-speed (wireless) Di2.

If you're looking for the 10-speed / 11-speed Di2 new user manual, visit my 10/11-speed Di2 beginner manual page.

Below is the list of subjects covered in this guide - click any of the links to skip ahead to the relevant section.

12-speed Di2 basics

• What does Di2 stand for?
• Shimano manuals on 12-speed Di2
• Do I need to switch the system on or off?
• How do I shift the bike? What shift buttons are there?
• The system is wireless?
• How about security? Can the bike be hacked??
• Mobile app? I connected and now the bike doesn't work
• How do you check the shifter battery level?
• Replacing the shifter battery
• How long does the main Di2 battery last between charges?
• Charging your Di2 bike
• What does the button on the rear derailleur do?
• Shift modes and Synchronized Shift
• Washing and transporting your Di2 bike
• Other resources

What does Di2 stand for?

Digital Integrated Intelligence, or just "Di2", is Shimano's electronic shifting. It has been around for a while now - the first DURA-ACE Di2 groupset was the 7970 series, released in 2009.

This 10-speed system uses a different wiring standard from all the Di2 groupsets that followed, and with the release of Ultegra 6770 (2011) Shimano introduced the EW-SD50 wires - and E-Tube. Then, a couple of years later, the SD300 wiring standard was introduced.

What is E-Tube? Essentially, it's just the name Shimano gave their electronic communication system. All Di2 systems (except 7970) communicate via E-Tube. While Shimano has never explicitly stated what it stands for, "Electronic-Tube" makes sense.

Di2 Software and Tools

Di2 windows software is called E-Tube Project, and the mobile app is E-Tube Project Cyclist. There's also the E-Tube RIDE mobile app, which basically turns your phone into a bike computer - you can only pair a limited set of sensors though.

If you'd like to read more on Di2 software, here's a page for you: Di2 E-Tube Software & Tools.

Shimano 12-speed Di2 Manuals

While I personally think the guide you're reading now is pretty thorough, it's impossible to cover everything. This page would just grow way too long.

Shimano actually has a pretty good documentation site - si.shimano.com. This is where you can find Exploded Views (EV), User Manuals (UM), and Dealer Manuals (DM) for all your components.

The regular user manuals aren't all that good, but the Dealer Manuals are. To find one, simply type your Di2 series' code in the search box, and then open the files labeled "DM". For example, if you're looking for 12-speed Ultegra manuals, type "R8150", hit enter, and open the relevant DM. Note that the hydraulic shift levers have model code R8170.

If you're on 12-speed DURA-ACE, then you type "R9250" into the search box. Again, use "R9270" to find hydraulic shift lever manuals.

I've uploaded the 12-speed Di2 manuals to the site as well, for your convenience.

• 12-speed Road Di2 General Dealer Manual
• 12-speed Gravel Di2 General Dealer Manual
• Road Rear Derailleur Dealer Manual
• Gravel Rear Derailleur Dealer Manual
• Rear Derailleur User Manual
• Road Front Derailleur Dealer Manual
• 105 / Gravel Front Derailleur Dealer Manual
• Hydraulic/Wireless Shift Lever Dealer Manual
• Rim brake (wired) Shift Lever Dealer Manual
• Satellite shifter / Rim brake Dealer Manual
• Battery Dealer Manual
• E-Tube Cyclist manual
• Shimano Torque Chart

If you'd like to know more about using the Shimano documentation, take a look at my page on using Shimano's documentation site: si.shimano.com.

Do I need to switch the system on or off?

Nope! You don't! There is no "on" or "off" switch.

For wired (or rim brake) Di2 systems, that's all there is to it - the main Di2 system is always on, always ready to shift. The only thing that goes into standby mode is the rear derailleur's BluetoothLE/ANT connectivity.

Most 12-speed Di2 bikes will be hydraulic disc brake systems though, and therefore also use wireless shift levers. In this case, you actually have to wake up the Di2 system before it'll work.

It will not shift the very first time you press a shift button. This first shift effectively wakes up the system.

You'll only have to wake up the system once every ride, or after a coffee stop - it goes into standby mode after 30 minutes of inactivity.

How do I shift the bike?

If you have DURA-ACE, Ultegra or GRX 12-speed Di2, you may have found the buttons on top of your shifter hoods, but those usually don't change the gears - you can set them up that way though (scroll down to 'mobile app').

So how do you shift a Di2 bike? How do you change gears with Di2? Simple! Just press the buttons on the side of each brake lever as shown in this image:

Shift the Di2 Front derailleur

In order to shift the front derailleur, you use the left lever and press either switch X (the larger button) or switch Y (smaller).

If you find it hard to remember which button shifts up or down, think of it this way: pressing the larger button will shift to a larger chainring. Pressing the smaller of the two buttons will shift to the small ring - an easier gear.

Shift the Di2 Rear derailleur

Shifting the rear derailleur works just like shifting the front derailleur - you press either switch on the side of the right shift lever.

Pressing switch X (larger button) will shift to an easier gear - a larger cog or sprocket. Pressing the Y button will shift to a smaller cog or sprocket - a harder gear.

Yes, there are buttons on the lever hoods (DURA-ACE / Ultegra / GRX)

So yeah - most road bike Di2 levers have buttons on top of the hoods, and the 12-speed levers are no exception.

Traditionally, the lever hood buttons are set up to perform wireless functions. They are set to 'D-fly Ch.1' and 'D-fly Ch. 2' by default.

D-Fly is perhaps a bit cryptic - it is Shimano's method of wirelessly communicating with accessories such as cameras, bike computers, lights, etc.

For most bike computers, these defaults will let you scroll through the screens and interact with them using the hood buttons. You can set these buttons up any way you like though. Just take a look at my page on setting up the hood buttons, and be sure to scroll down to the 'using the mobile app' section.

Personally, I like to set the left hood button to "function". This lets that button mirror the one on the rear derailleur, letting you switch synchro shift mode or enter adjustment mode while riding the bike.

It's all up to you though, so experiment and figure out what works best for you.

The system is wireless?

Yes. Well... sort of. 12-speed Di2 systems support wireless shifting for hydraulic disc brake bikes only. Rim brake bikes can only be set up fully wired.

Shift signals are sent wirelessly from the shift levers to the rear derailleur. Your rear derailleur is the system's main BluetoothLE/ANT hub (transmitter/receiver).

It's not all wireless though - both derailleurs are still wired to the main battery, using a single wire each. The main battery (BT-DN300) is usually located in the seatpost.

Wireless Di2 shift levers run on CR1632 batteries. These should last about two years for DURA-ACE and Ultegra, and four years for 105 Di2 and 12-speed GRX (two batteries per shift lever).

Changing the batteries is a simple, 1-minute job. If you'd like to know how that goes, read my guide on replacing wireless shift lever batteries.

Note that even if your shift levers support wireless shifting, you can use them fully wired too (except the 105 shift levers). Doing so increases the main battery life by 50%.

If you're running the shift levers wired, and the wire gets disconnected somehow, it'll automatically switch to wireless mode in about 10 seconds - neat!

The downside to the wireless hydraulic shift levers? You cannot easily update them. In fact, updating wireless shift levers is a bit of a hassle.

How about security? Can the bike be hacked?

In the summer of 2024 a group of researchers published a paper on wireless shifting vulnerabilities. Specifically, they investigated Shimano Di2 vulnerabilities, and found a couple of different methods of attacking the system: replay attacks and jamming entire groups of bikes, for example.

A few weeks later Shimano published firmware updates for all twelve-speed rear derailleurs, and the wireless road and gravel shifters.

There is no reason to believe anyone has actually had their bikes hacked, and since it'd require an attacker to wait for cyclists, have a laptop listen to their shift signals, and then re-play those signals right back at the cyclist, the chances are slim.

Still, security cannot be ignored, and since there is updated firmware available, I recommend you install that - or have it installed by your bike shop.

You can read more about the security updates in Shimano's firmware update FAQ.

Connect to phones, bike computers

Since the wireless connectivity is in the rear derailleur, you can connect any 12-speed Di2 bike to your bike computer (Wahoo, Garmin, Sigma, etc.).

E-Tube Cyclist (mobile app)

To connect to your mobile phone, download E-Tube Cyclist from the iOS or Android app store.

Then, make sure Bluetooth is enabled on your phone, and open E-Tube Cyclist.

On your 12-speed rear derailleur, press-and-hold the button for 0.5 - 2 seconds. The LED will flash blue, indicating that the system is in BluetoothLE connection mode.

You then use E-Tube Cyclist to register a new bike, or connect to a previously added bike.

Connect bicycle computers

Connecting to bike computers (like a Garmin, or Wahoo, Sigma, etc.) is relatively simple. Usually you 'wake up' the Di2 system by shifting once, or by pressing the button on the rear derailleur.

Your bike computer should then be able to see the Di2 system, and connect to it.

How you do this exactly depends on the bike computer you use. Here are the help pages for the most common ones:

• Garmin: configuring Di2 on a Garmin device
• Wahoo: BetterShifting.com // Wahoo.com
• Sigma: Rox 12.0 // Rox 11.0 // Rox 10.0
• Bryton: Setup on youtube

The HammerHead Karoo and Karoo 2 are special cases. Shimano forced SRAM to remove Di2 support from the Karoo devices in 2021. A helpful developer built an app that adds Di2 support back to the Karoo devices.

Mobile app? I connected and now the bike no longer works!

Don't worry - your bike is fine. You see, as long as your phone is connected to the bike using E-Tube Cyclist, the bike won't respond to any commands. This is supposed to happen, but it does cause confusion and near-panic attacks among some new Di2 owners.

To restore the bike, reconnect using the mobile app and then simply press the disconnect button. You should then be able to shift again.

How do you check the shifter battery level?

If your bike has wireless shift levers, you'll have to replace the batteries after about two years (the 105 Di2 shifter batteries will last four years). Checking the battery status is really easy - you simply press and hold both shift buttons for about 0.5 seconds.

The lever's LED will then switch on, showing you a rough battery level indication:

• Green: 11% to 100% battery
• Red: 1% to 10% battery level
• No LED: 0%

Once the (CR1632) battery reaches 10%, you've got about a month to replace it. It'll go completely flat after that.

Replacing the shift lever battery

Changing the batteries is really simple, and only takes a couple of minutes. Watch the embedded video above, or read all about this in the Replace Wireless Shift Lever Battery Guide.

How long does the main Di2 battery last between charges?

This is a tricky one - twelve-speed Di2 hasn't been around for a very long time, so all we have to go on is Shimano's own (worst-case) estimation: about 1000km.

This estimation takes into account quite a lot of (battery-hungry) front derailleur shifts, and personally, I'd expect the battery to last about 1500km between charges.

If you'd like a bit more range, consider connecting the shift levers to the battery using wires. This increases battery life by approximately 50%.

Checking your Di2 battery status

Checking the main Di2 battery charge level is really easy - you just press the rear derailleur button.

Pressing the button for 0.5 seconds or less will turn on the LED, indicating the remaining battery charge.

• Solid green: 100% - 51%
• Flashing green: 50% to 26%
• Red: 25% to 1%
• Off: 0%

A blue LED turns on after the battery check?!?

Don't worry, this is completely normal - the blue LED indicates the selected shift mode.

What are shift modes you say? Scroll down to the Synchronized Shift section for more information on shift modes.

For a quick and handy guide to the Di2 LEDs and buttons, take a look at the Di2 Cheat Sheets right here. They're an easy reference guide and I use them all the time myself.

Once your battery level drops below 10%, the front derailleur will stop working. You can then shift only the rear derailleur until the battery goes completely flat.

Charging your Di2 bike

Since the time between charges is pretty good, this is a subject most new Di2 riders don't think of until they actually have to charge their battery.

To charge the bike, locate your charge cable (EW-EC300), an adapter block or computer, and then take a good look at your rear derailleur.

The charge port is located on the rear derailleur, all the way at the back of the bike. You open up the charge port, connect the charging cable, and plug it in.

That's it! the LED will light up blue, indicating that the battery is being charged.

Charging the bike should take between 1 and 3 hours, depending on the adapter used, as well as the remaining battery level. The LED will turn off when the battery is fully charged.

If you're trying to charge the bike and the LED flashes red, then you may need to use a different USB port or adapter.

Note that any adapter you use should have a current capacity of 1.0A or higher.

Finally, you cannot operate the derailleurs while charging - they won't respond to shift commands. Charging the battery using a dynamo hub or power bank while riding isn't an option, unfortunately.

What does the button on the rear derailleur do?

If you've read the rest of this guide, you may have seen that the rear derailleur button lets you check the main battery charge level, and can trigger BluetoothLE connection mode.

That's not all it does though - it can do so much more.

I'll explain all of this in a minute, but also want to direct your attention to my Di2 Cheat Sheets. The cheat sheets explain what the buttons do, and what the LEDs mean. Download them, print them, and keep them in the garage, close to your bike. That way you never have to wonder what the LEDs mean.

Interested? Download the Di2 Cheat Sheets.

Pressing the button twice switches the selected synchronized shift mode. The LED will then indicate what mode you just switched to:

• Blue: manual mode.
• Flashing blue, twice: Shift mode one (default semi-synchro).
• Flashing blue three times: Shift mode two (default full-synchro).

Not sure what synchronized shifting is? Read more on that in the next section.

A single, short (0.5 seconds), press of the button will show the battery level using the LED.

You can trigger BluetoothLE connection mode by holding the button 0.5s - 2s. The LED will flash blue as long as the bike is in connection mode.

Next, adjustment mode. Hold the button for 2s - 5s, and the LED will turn yellow. You can then adjust the derailleurs.

Finally, you can use the button to pair the wireless shift levers. In case you can't or won't use the mobile app.

Resetting the crash protect isn't done through the button like it is on previous generations.

Instead, you now simply shift all the way up and down the cassette. There's only one direction the rear derailleur will go when it is in crash mode, so you cannot get this wrong.

Shift modes and Synchronized Shift

All 12-speed Di2 road bikes support different shift modes and synchronized shift.

What is synchro shift, you ask?

Basically, it is a system shift modes and presets, that will automatically shift the front or rear derailleur, depending on your gear shifts.

You can make full synchro and semi synchro presets. This is what they do:

• Semi-synchro: This is the default shift mode for S1. When set to this mode, the bike automatically shifts the rear derailleur when you shift the front derailleur, to minimise the jump in gear ratio.
• Full-synchro: Your front derailleurs shifts automatically when the rear derailleur reaches a certain gear. This is the default setting for shift mode 2 (S2).

Finally, there's also manual mode. In this mode the bike doesn't do any shifting for you.

Shift presets

While you can make a virtually unlimited amount of presets using E-Tube Project Cyclist, you can have only two presets stored on the bike at any time - S1 and S2.

I've written a pretty big 'complete guide' on Synchronized Shift before, so read that if you want to know everything there is to know about synchronized shifting.

Note that I've moved setting up synchronized shift using the mobile app to its own page.

You can change between the shift modes by double-pressing the button on your rear derailleur. When you do this the bike cycles through three modes, indicated by the LED:

• Blue (2 seconds): Manual shift
• Flashing blue (2 times): Shift mode 1
• Flashing blue (3 times): Shift mode 2

More information on these shift modes can be found in the Synchroshift guide: Complete guide to Synchro Shift.

Washing and transporting your Di2 bike

When it comes to washing your bike don't need to take special care of the Di2 system. Your bike won't electrocute you when riding in the rain, and it also won't spontaneously explode if you get it wet washing your bike.

Just like you would with a mechanically shifted bike, use water and soap or any other mild cleaner. Take care not to contaminate your disc brakes.

As long as all Di2 ports have either Di2 wires or dummy plugs in them, they're pretty water-resistant.

Don't worry about getting Di2 parts wet, but also don't pressure wash your derailleurs. They can take some water, but are not completely water-proof. To prevent oxidation, wipe off excess water and dry your Di2 parts using a towel.

How do I safely transport my bike?

Not a whole lot can go wrong with transporting your bike. The main thing you should keep in mind is that a Di2 derailleur will try to shift, and keep trying to shift, as long as a shift button is pressed.

This means that if you put your bike in the back of a car, you should take care that your bike is not trying to shift all the way to your destination - that would mean getting there with a flat battery.

Speaking of batteries - it's a good idea to bring your charger with you, even if you just charged your battery.

If you've had the bike for a while, bringing a spare CR1632 battery can be a good idea too.

• CR1632 on eBay (affiliate link)
• CR1632 on Amazon (affiliate link)

Other resources

There is a lot of other information on Di2 out there, you just have to know where to look. Carlton Bale has an excellent page with in-depth Di2 information, GPLama / Shane Miller has a bunch of videos up on Youtube, and of course, there's GCN and GCN Tech as well.

I mentioned this earlier, but I'll do it again: the Shimano manuals are a really good source of information. Especially on setting up and bike and troubleshooting issues.

Help! Tell me more!

This is a beginner guide to 12-speed Di2, and it (intentionally) doesn't cover everything.

If you have a question or problem, and it isn't covered in the installation guides or the Frequently Asked Questions, feel free to send me a message - or leave a comment below.

I'll do my best to help you as soon as I can.