SpeedBox 1.5 Tuning Chip for Bosch Performance Line SX Gen4 (BDU3144/BDU3145)

SpeedBox 1.5 is a tuning chip for Bosch Performance Line SX 4th-generation motors (BDU3144, BDU3145) on Smart System e-bikes with the valve-mounted Bosch Rim Magnet. It removes the factory 25 km/h speed limiter; the limit can be set up to 99 km/h, but the manufacturer recommends not exceeding 35 km/h to avoid error codes.

Installation is simplified: there is no separate magnet simulator to position, and the chip connects with original connectors.

Real speed is not shown on the bike's display during the ride; correct distance appears once the post-ride countdown finishes. For live speed on your phone, see the B.Tuning version.

Key Features

• Maximum speed: unlimited (35 km/h maximum recommended)
• Tuning status shown on display: 3.5 km/h = on, 2.5 km/h = off
• Correct travelled distance shown after the post-ride countdown finishes
• Speed limit: adjustable up to 99 km/h
• Real speed on bike display: no
• Activation: WALK function or - + - + button sequence (only when stationary)
• Simplified installation: no magnet simulator to position; uses original connectors
• SpeedBox Connect app: not supported
• Designed for motors mounted with 2 diagonal screws

Compatibility

• Bosch Performance Line SX 4th-generation motors: BDU3144, BDU3145
• E-bikes with the Bosch Rim Magnet (magnet attached to the valve)
• Current Bosch software versions
• Not compatible with standard spoke-mounted magnets
• Not compatible with Bosch ABS system
• Not compatible with the SpeedBox Connect app

How to Use

1. Before installing on a new bike, ride at least 10 km.
2. Connect the male and female connectors in the direction of the lock; do not twist or rotate them while connecting.
3. With the bike stationary, activate tuning by holding the '-' button to engage WALK assist (or use the - + - + sequence if WALK is not enabled). The display shows 3.5 km/h when tuning is on.
4. Repeat to deactivate; the display shows 2.5 km/h and the limit returns to 25 km/h.
5. Set a custom speed limit (up to 99 km/h) by switching modes TURBO, eMTB, TOUR+, ECO, TOUR+, eMTB, TURBO. The display shows the selected limit (2.5 km/h = 25 km/h, 3.0 km/h = 30 km/h, 3.5 km/h = 35 km/h), which is saved after 15 seconds of inactivity.
6. After each ride, leave the bike switched on until the display shows 0.0 km/h and do not remove the display before this countdown finishes; it can take several minutes after a long ride. For short stops keep one foot on the pedal to prevent the countdown starting.

Good to Know

• Check your motor model, magnet type and motor space before ordering.
• Do not activate or deactivate tuning while riding.
• Disable automatic firmware updates in the eBike Flow app. Firmware updates can make the chip inoperable.
• SpeedBox warranty does not cover malfunctions caused by firmware updates.
• Bluetooth version: SB15BT-B.
• For BDU3142/BDU3143 motors, see SpeedBox 1.4 (SB14-B / SB14BT-B).

Legal and Safety Notice

This tuning chip changes the e-bike's factory speed limit and assistance settings. A modified e-bike may not be legal to ride on public roads, cycle paths or other public areas; SpeedBox products are intended for use on private property, at the rider's own risk. Installation may void the e-bike manufacturer's warranty. Installation by a qualified technician is recommended. Always wear appropriate protective gear.