SpeedBox 1.4 Tuning Chip for Bosch Performance Line SX Gen4 (BDU3142/BDU3143)
Fits Bosch Performance Line SX Gen4 motors BDU3142 and BDU3143 on Smart System bikes with the valve-mounted Rim Magnet. Tuning chip that removes the speed limiter (35 km/h maximum recommended) with simplified installation and no magnet simulator.
SpeedBox 1.4 Tuning Chip for Bosch Performance Line SX Gen4 (BDU3142/BDU3143)
SpeedBox 1.4 is a tuning chip for Bosch Performance Line SX 4th-generation motors (BDU3142, BDU3143) 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 top screws
Compatibility
Bosch Performance Line SX 4th-generation motors: BDU3142, BDU3143
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
Before installing on a new bike, ride at least 10 km.
Connect the male and female connectors in the direction of the lock; do not twist or rotate them while connecting.
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.
Repeat to deactivate; the display shows 2.5 km/h and the limit returns to 25 km/h.
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.
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: SB14BT-B.
For BDU3144/BDU3145 motors, see SpeedBox 1.5 (SB15-B / SB15BT-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.
