Shimano Di2 Button Customization Guide: Build Your Own Shifting Logic

The Complete Guide to Customizing Shimano Di2 Buttons

The advantage of Shimano’s Di2 electronic shifting system isn’t just fast, precise shifting — it’s also the highly flexible button customization it offers. Through the E-Tube Project app, you can redefine what every single button does, enable automatic Synchro Shift, adjust shifting speed, and even set up multi-shift jumps. This article uses the 12-speed R9200/R8100 series as the main example.

E-Tube Project Basic Setup

How to Connect

The Di2 12-speed system supports wireless Bluetooth connection, so no extra connector hardware is needed:

1. Download the E-Tube Project app (iOS / Android)
2. Press and hold the function button on the shifter to enter pairing mode (button location varies by model)
3. Search for and connect to your Di2 system in the app
4. For a first-time connection, it’s recommended to run a firmware update first

Note: 11-speed Di2 (R9150/R8050) requires the desktop version of E-Tube Project via an SM-PCE02 or SM-BCR2 to configure.

Button Assignment

Default Button Assignment

The 12-speed Di2 shifters (ST-R9270/R8170) each have two shift paddles per side:

Button Position	Default Function (Left Shifter)	Default Function (Right Shifter)
Large paddle	Front derailleur: small ring → big ring	Rear derailleur: easier gear (larger cog)
Small paddle	Front derailleur: big ring → small ring	Rear derailleur: harder gear (smaller cog)

Customization Options

E-Tube Project lets you reassign each button to any one of the following functions:

• Rear derailleur shift up
• Rear derailleur shift down
• Front derailleur shift up
• Front derailleur shift down
• Rear derailleur multi-shift up (jump 2-3 gears at once)
• Rear derailleur multi-shift down

Popular Custom Configurations

Option 1: Left-Hand Full Rear Derailleur Control

Suited for riders who prefer left-hand shifting control, or when the front derailleur is set to fully automatic Synchro Shift mode.

Button	Left Shifter	Right Shifter
Large paddle	Rear: easier gear	Rear: easier gear
Small paddle	Rear: harder gear	Rear: harder gear

The front derailleur is fully controlled automatically by Synchro Shift.

Option 2: Mirrored Dual Control

Both shifters have identical functions, so either hand can perform every operation.

Button	Left Shifter	Right Shifter
Large paddle	Rear: easier gear	Rear: easier gear
Small paddle	Rear: harder gear	Rear: harder gear
Press both together	Front derailleur toggle	Front derailleur toggle

Option 3: Sprinter’s Setup

The right hand handles everyday fine adjustments while the left hand handles large gear jumps.

Button	Left Shifter	Right Shifter
Large paddle	Rear: multi-shift easier (+3)	Rear: easier (+1)
Small paddle	Rear: multi-shift harder (-3)	Rear: harder (-1)

Synchro Shift Explained

Synchro Shift is one of Di2’s most powerful features — it automatically switches the front derailleur based on the current rear derailleur position.

Three Modes

1. Full Synchro (fully automatic)

The front derailleur is completely automatic; the rider only needs to control the rear derailleur. The system automatically determines when to shift between chainrings based on the current gear ratio.

• Pros: You never have to think about the front derailleur, letting you focus purely on riding
• Cons: The timing of front shifts may not match your personal preference
• Best for: Casual riders who don’t want to think about shifting logic

2. Semi Synchro (semi-automatic)

The front derailleur is still shifted manually, but when you switch chainrings, the rear derailleur automatically compensates for the resulting jump in gear ratio.

For example: when switching from 50-17 down to the 34-tooth small ring, the rear derailleur will automatically jump from 17T to 12T to maintain a similar gear ratio, avoiding a sudden drop in resistance.

• Pros: Smoother chainring changes without a sudden drop in pedaling resistance
• Cons: The auto-compensated gear may not always be the one you wanted
• Best for: Most riders — this is the recommended mode to try first

3. Manual

Works just like traditional mechanical shifting logic, with the front and rear derailleurs fully independent of each other.

Synchro Shift Adjustment Parameters

In E-Tube Project you can configure:

• Shift trigger point: which rear gear position triggers an automatic front shift
• Shift range: how many rear gear positions the auto-compensation is allowed to span
• S1/S2 mode switching: you can set up two different groups of Synchro parameters and switch between them quickly while riding

Multi-Shift Settings

Press-and-Hold Multi-Shift

Di2 supports continuous shifting by holding down the shift button, and you can adjust:

• Trigger delay: how long you must hold the button before continuous shifting begins (300-500ms recommended)
• Shift speed: the interval between each shift during continuous shifting
• Maximum consecutive shifts: how many gears can be jumped in a single continuous shift (limiting it to 3-4 gears is recommended to avoid overshooting)

Shift Speed Adjustment

The rear derailleur’s shift speed can be adjusted in E-Tube:

Setting	Effect	Best For
Fast	Shifts more quickly but with a more noticeable jolt	Racing, flat terrain
Standard	Balances speed and smoothness	General riding
Slow	Smoother, quieter shifting	Climbing, long-distance riding

Trim Adjustment

Front derailleur trim on Di2 is handled automatically, but you can fine-tune the front derailleur’s position through E-Tube:

• Inner limit: prevents the chain from rubbing the front derailleur cage when in the small ring + largest cog combination
• Outer limit: prevents the chain from rubbing the front derailleur cage when in the big ring + smallest cog combination
• Adjustment increment: 0.1mm per step — it’s recommended to adjust only one step at a time

Firmware Update Notes

1. Ensure sufficient battery before updating: 50% or higher is recommended
2. Do not interrupt the update process: an interrupted firmware update may render the system unusable
3. Recheck your settings after updating: some updates may reset custom configurations
4. Update components one at a time: if the front derailleur, rear derailleur, and shifters all have updates available, it’s best to complete them one by one

Practical Tips

• Switching modes while riding: you can set a specific combination of pressing both left and right shifter buttons simultaneously to switch between S1/S2 modes
• Battery display: connecting via E-Tube shows the exact battery percentage — the built-in Di2 battery typically lasts about 1,000-2,000 km
• Backup your settings: E-Tube Project can save your configuration profile, letting you quickly restore it after a bike swap or reset
• Pairing with a bike computer: an ANT+ connection to your bike computer can display gear position and battery level in real time

Recommended Setup for Beginners

If you’ve just gotten a Di2 system, it’s recommended to start with the following setup:

1. Enable Semi Synchro mode
2. Keep the right shifter on the default rear derailleur control
3. Set the left shifter to rear multi-shift (large paddle +3, small paddle -3)
4. Let Semi Synchro handle the front derailleur automatically
5. After riding for a while, fine-tune further based on your personal preferences

The greatest value of electronic shifting lies in being able to continuously experiment and adjust until you find the shifting logic that suits you best. Don’t be afraid to experiment — you can always restore the default settings at any time.

Related Reading

• A Beginner’s Guide to Electronic Shifting (Di2/eTap): Is It Worth Upgrading?
• In-Depth Review of Electronic Shifting Systems: Comparing Shimano Di2 vs SRAM eTap on Usability, Reliability, and Upgrade Cost
• Shimano 105 R7100 Fully Explained: The Best Entry Point into Electronic Shifting
• A Real-World Comparison of Di2/eTap/EPS Electronic Shifting vs Mechanical Shifting