Bosch Gen4 Tuning 2026: How to correctly identify BES2 + suitable solutions for Bosch CX Gen4

Who after Bosch Gen4 Tuning, Bosch CX Gen4 Tuning or Make Bosch Gen4 faster In many cases, the search refers to the classic Bosch Gen4 world of the model years. 2020 / 2021Technically important: This page deals exclusively with... Bosch Gen4 with BES2 system – so not the later one Bosch Smart System / BES3.

If your e-bike is equipped with eBike Flow App, LED Remote, system controller, Purion 200, Kiox 300 or Kiox 500 If you're working with a Bosch Smart System, you're generally not in the classic Gen4 BES2 world. In that case, you need the Bosch Smart System logic, not the classic Bosch Gen4 solutions described here.

Go directly to the product overview:
Bosch Gen4 Tuning Products

What is meant by Bosch Gen4 / BES2?

In day-to-day shop and support operations Bosch Gen4 mostly for the classic BES2 generation of the model years 2020 / 2021The following is particularly well-known: Bosch Performance Line CX Gen4, often with the BDU identifier BDU450 respectively BDU450 CX.

This Gen4 BES2 world is technically a different platform than the later one. Bosch Smart System / BES3Therefore, when choosing any product, you should first clarify: Is it really a Bosch Gen4 BES2 – or already a... Smart System?

Bosch Gen4 BES2 or Bosch Smart System?

feature	Bosch Gen4 BES2	Bosch Smart System / BES3
Typical years	2020 / 2021	from 2022
App	No eBike Flow app as the system core	eBike Flow App
Typical displays	Purion, Intuvia, Kiox, Nyon	Kiox 300 / 500, Purion 200, LED Remote
Typical solution	EBT Unlock Key, RedPed, VOLspeed, SpeedBox, PearTune	EBTsmart Unlock Key

Error code 504 on Bosch Gen4

Bosch Gen4 / BES2 already incorporates anti-tuning logic. The most well-known example is... Error code 504It can occur if the system detects implausible speed signals or tampering.

That's why Bosch Gen4 is important:

• Use only suitable Gen4/BES2 solutions.
• Do not confuse Smart System products with BES2
• Prefer moderate settings
• Check compatibility before firmware updates
• In case of problems, first check the sensor, magnet position and system status.

The most important tuning solutions for Bosch Gen4 / BES2

1. EBT Unlock Key – digital main solution without a chip

The EBT Unlock Key is currently one of the most interesting solutions for many Bosch Gen2, Gen3 and Gen4 e-bikes with BES2Activation is done via USB and browser – without a classic chip, without a dongle and without permanently installed additional hardware on the bike.

• digital activation via license code
• browser-based via USB
• no additional hardware on the bike
• reversible
• for many Bosch Gen2–Gen4 / BES2 systems
• not for Bosch Smart System / BES3

Important: With Bosch Gen2–Gen4 / BES2, the display shows split or differing values ​​after activation.

EBT Unlock Key more blog posts

2. RedPed 3 for Bosch

The RedPed 3 It is one of Bosch's most feature-rich solutions. It offers app control, numerous settings, and comprehensive driving data.

Compatible with many Bosch models Active Line, Performance Line, Performance Line CX, Cargo Line as well as Bosch Gen4 / BES2. Not compatible with Bosch Smart System / BES3.

3. VOLspeed V4 for Bosch Gen4

The VOLspeed V4 is one of the best-known modular solutions for Bosch Gen4 / BES2. The individually adjustable maximum speed and the optional dynamic mode are particularly valued.

4. SpeedBox 3.0 for Bosch

The SpeedBox 3.0 is a classic modular solution for Bosch Gen4 / BES2. It is also available as SpeedBox 3.0 B.Tuning Available with app features.

5. PearTune MSO for Bosch

PearTune MSO 4.0 and PearTune MSO 3.0 are proven module solutions for Bosch Gen2, Gen3 and Gen4 / BES2.

6. Badass Box 4 for Bosch

The Badass Box 4 is a contactless solution for Bosch BES2 bikes. It is attached to the speed sensor; the spoke magnet is also repositioned.

Badass Box 4 for Bosch
Badass Box 4 Slim Set
Badass Box 4 X-Set
Badass Box 4 G4 set

7. Further solutions: sIMPLEk and MBIQ

Non-personal or anonymized information remains protected by tax secrecy. Disclosure to third parties is only allowed if no identification is possible and both states confirm that no harm to tax administration will occur. sIMPLEk and MBIQ remain relevant in the Bosch Gen4 BES2 area – depending on the desired logic as a kit, stick, sensor or plugin solution.

sIMPLEk Overview
MBIQ-P Plugin for Bosch
MBIQ-S Sensor for Bosch

Comparison: Which Bosch Gen4 solution is the right one?

Solution	Concept	Size	Important notes
EBT Unlock Key	digital license	no hardware on the bike	first modern main solution for BES2
RedPed 3	Module with app	many settings	not Smart System
VOLspeed	module	Dynamic mode, adjustable	check BES2
SpeedBox	module	classic solution	Choose the correct option
Badass Box	external box	quick to assemble	Note sensor/magnet position

Conclusion: Bosch Gen4 / BES2 remains a strong, independent tuning world.

The Bosch Gen4 / BES2 platform for model years 2020/2021 remains one of the most important Bosch systems overall. At the same time, this platform is further enhanced by Error code 504 and the anti-tuning logic has become more technical than older Bosch systems.

The most important rule is:

• Bosch Gen4 / BES2 = classic Bosch world 2020 / 2021
• Bosch Smart System / BES3 = new smart system world from 2022
• EBT Unlock Key = modern digital main solution for many BES2 bikes
• EBTsmart Unlock Key = Smart system solution for BES3

All current products for Bosch Gen4 / BES2 can be found here:
Bosch Gen4 Tuning Overview

Go to the Bosch Tuning Guide
Go to the EBT Unlock Key
EBTsmart Unlock Key