RimBoost V2.37: for Bosch BES3 with rim magnet (BDU37)

RimBoost V2.37: Chip for Bosch Smart System (BDU37) with rim magnet

Second generation tuning tool for unlocking Bosch Gen4 Smart System E-bikes with rim magnets!

With this tool, you can finally unlock the full potential of your Bosch e-bike. The 25 km/h speed limit is lifted, allowing you to ride much faster and more dynamically – you'll experience a whole new riding experience! In contrast to the first version of the RimBoost chip, this new "V2" variant is compatible with all current Bosch Smart System firmware versions.

However, we still advise against performing updates on your Bosch e-bike - compatibility with the tuning may no longer be guaranteed afterward! The warranty for RimBoost chips applies not availabe in the event of malfunctions caused by updates to the e-bike drive system.

Please note: This tuning chip was specially developed for Bosch Smart System E-Bike drives of the fourth generation (Bosch Gen4), the one Rim magnets instead of a classic spoke magnet (more detailed information can be found below under "Compatibility"). You can recognize Bosch Gen4 e-bikes by the internal technical identifier "BDU37".

If you have a Bosch e-bike from fifth generation (Bosch Gen5) you need the RimBoost V2.38The Bosch Gen5 was launched in early 2025. You can recognize these models by the internal identifier "BDU38".

Important: The tuning chips are NOT compatible if your Bosch Smart System E-Bike with rim magnet with ABS or ABS-Pro - for Bosch BES3 bikes with ABS or ABS Pro there are currently no Tuning solution.

Please note: Installation of this tuning is not easy and requires some technical skill. Please only order this product if you feel confident about installing it yourself.

Note: The new edition of the RimBoost has been successfully released. We're always about three weeks behind on delivery when you place an order. So if you order now, we'll ship in two to three weeks. Therefore, we're keeping the product on "pre-order."

About RimBoost V2.37

The RimBoost V2.37 is the optimized second generation of a tuning chip, which was once again developed by the absolute tuning specialists from “MountainTuning“ was developed. We owe the MountainTuning development team has developed a whole range of outstanding tuning solutions for various e-bike drive systems. For a long time, it was considered technically impossible to Bosch Smart System to tune e-bikes with rim magnet - until MountainTuning tackled the problem, and with success! In fact, the RimBoost Tuning Chips are the first working tuning solution for Bosch Smart System (BES3) e-bikes with rim magnet at all (assuming they do not have ABS or ABS Pro).

The RimBoost V2.37 tuning chip lifts the 25km/h speed limit of Bosch Gen5 Smart System E-bikes with a rim magnet unlock completely, allowing theoretically unlimited speeds with full motor support. In reality, unlocking allows speeds of up to 42 km/h to be reached – of course, depending on external factors such as load or tire pressure.

Bosch Anti-Tuning Software does not work

To test the reliability of this tuning chip, we conducted extensive test drives. The integrated anti-tuning software of the Bosch Smart Systems not availabe and there were also no error messages The tuning chip thus appears to be insensitive to anti-tuning measures by Bosch. This applies to all current Bosch Smart System firmware and software variants.

However, we cannot give a 100 percent guarantee that error messages will not occur when using the chip. There is now evidence that the well-known Bosch error "524001" sometimes occurs even without the use of a tuning tool. However, this has not occurred during any of our extensive test drives so far. Nevertheless, we cannot completely rule out the possibility of the 524001 error occurring. 

To ensure the highest level of quality, only high-quality components are used in the production of RimBoost tuning chips.

RimBoost V2.38 - Installation

While installing the RimBoost tuning chip only requires a few specific steps, it's not exactly straightforward and requires some technical skill. Please only order this product if you're confident installing the tuning yourself. Below, we explain how the RimBoost chip works and how to install the tuning:

First of all: RimBoost is a tuning chip that is permanently connected to the engine compartment. The chip has a total of four wires – two wires for power, a new sensor at the end of the third wire, and an electromagnet on the fourth wire.

Step 1: Remove the rim magnet and attach the new spoke magnet

With RimBoost Tuning, the original Bosch rim magnet must be removed so that it can no longer transmit signals to the original Bosch sensor. The rim magnet is replaced by the sensor on the RimBoost chip – this, by the way, is the well-known sensor already found on "normal" Bosch e-bikes. without Rim magnet (on these models, the sensor is located on the rear wheel swingarm). This allows the included RimBoost spoke magnet to transmit the speed to the sensor.

Step 2: Attach the electromagnet 

The RimBoost sensor transmits data to the RimBoost chip, which in turn transmits signals to the electromagnet. The electromagnet must be attached to the motor cover with strong double-sided 3M adhesive tape, between the rear wheel and the Bosch sensor installed in the engine compartment. A smart installation routine shows you the optimal position of the electromagnet on the motor housing. The electromagnet is so inconspicuous that it is barely noticeable and barely changes the appearance of the e-MTB (see photo). Sometimes the electromagnet can also be installed inside the motor cover. 

Tip: To avoid losing the Bosch rim magnet, simply attach it to the front wheel. This way, it won't get lost. The included spoke magnet attaches to the RimBoost sensor on the spoke, making the tuning almost indistinguishable from the original removal system.

How does the RimBoost chip work?

Once installed, the RimBoost chip's electromagnet transmits a modified signal to the original Bosch sensor located inside the motor housing while driving. This modified signal overrides the 25 km/h speed limit and cancels the preset speed limit. As a result, you can drive much faster than before with full motor support – depending on factors such as load and tire pressure, speeds of up to 42 km/h can be reached. This finally unlocks the true potential of your Bosch Smart System Motors unfold.

Important note: Due to the special functionality of this tuning, the e-bike display no show more real data (route, current speed, etc.).

Our advice: To display the correct data while on the go, you can also use a GPS-enabled phone. It's best to attach it directly to the handlebars so you always have a clear view of the display. brackets can be found in our shop.

No extra battery is required for the RimBoost chip, as the power supply is provided by the e-bike battery.  

The tuning can be uninstalled at any time

If necessary, you can restore the e-bike to its original condition; essentially, all you need to do is replace the magnet. Uninstall the new spoke magnet and reinstall the original Bosch rim magnet. The e-bike will then function normally again—as if no tuning had ever been installed (maximum speed 25 km/h and actual values ​​on the display). 

Compatibility

The RimBoost V2.37 tuning chip is only compatible with:

-Bosch Gen4 e-bikes with Bosch Smart System (BES3) and with rim magnet (Rim Magnet). Compatible with the latest software and firmware versions.   

-Compatible up to Bosch Update 17.16.0, therefore also with the Bosch Update 16.19.0 from July 2025 (100 Nm Update). Also compatible with all older software versions.

Bosch Gen4 e-bikes can be identified by the internal technical identifier "BDU37" ("Bosch Drive Unit 37"). Please check before ordering whether it is actually a Bosch Smart System e-bike of the fourth generation (Gen4). Please refer to your bike's data sheet or the manufacturer's website.

Important - please note:

-The tuning chip is CAN'T compatible with e-bikes with ABS or ABS-Pro.

-The Bosch Gen4 was first introduced in 2020 - so older models CANNOT be Bosch Gen4.

-Since the beginning of 2025, the Bosch Gen4 has been gradually replaced by the Bosch Gen5 - you can recognize the Gen5 by the internal identifier "BDU38" ("Bosch Drive Unit 38"). Do you have a Bosch Gen5 Smart System E-Bike ("BDU38") with rim magnet, you must RimBoost V2.38 choose!

Important: The RimBoost tunings are exclusively compatible with Bosch Smart System E-Bikes with rim magnet (Rim magnet / sensor on the rear wheel valve). These bikes can be identified by the rather large magnet or speed sensor on the rear wheel valve! 

Image of rim magnet:

 

About the Bosch rim magnet

Until recently, almost all Bosch Smart System E-bikes have a so-called "spoke magnet" (magnet on the spoke). For models with spoke magnets, there were and are numerous tuning tools with which the bikes can be unlocked (removal of the 25 km/h limit). However, in recent times, it has become increasingly common for Bosch Smart System E-Bikes are equipped with a rim magnet instead of a spoke magnet - especially CUBE E-Bikes with Bosch Smart System drives. The rim magnet records all important riding data, so no additional speed sensor is required. The data is recorded directly in the motor. Due to this innovative operating principle, it was not possible to unlock Bosch e-bikes with rim magnets for a long time. The RimBoost Tuning Chips are the first functioning solution with which Bosch e-bikes with rim magnets can be tuned. Owners of CUBE e-bikes with rim magnets can breathe a sigh of relief, as there is finally a real tuning solution: The RimBoost Tuning Chips remove the 25 km/h limit WITHOUT activating the dreaded Bosch anti-tuning software. RimBoost Tuning V2 is the second, technically revised and optimized version of these tuning chips - RimBoost V2.37 works even more effectively than the original model and is now even compatible with all current Bosch firmware versions.

So: Especially if you have a CUBE e-bike with Bosch Smart System drive, you should definitely check whether the bike has a spoke or rim magnet (see photo above) BEFORE ordering a tuning chip. If it's a Bosch Gen4 ("BDU37") e-bike with a rim magnet (but WITHOUT ABS or ABS Pro), this tuning chip is perfect for you. We recommend pre-ordering your own copy now, as demand for these chips is enormous. 

About the Bosch BDU37 engine: 

The Bosch BDU37, also known as Performance Line The fourth generation CX is a powerful e-bike motor that has established itself particularly in the e-mountain bike segment.

Designation and generation: The BDU37 is officially known as Performance Line CX Gen4. In technical documentation and forums, it is often referred to by the internal designation BDU37 ("Bosch Drive Unit with serial number 37"). This nomenclature serves for unique identification within the Bosch product range.

Period of use: The BDU37 was introduced in the 2020 model year and has since been installed in numerous e-bike models. With the introduction of the successor model BDU38 (Performance Line CX Gen5) in 2025, production of the BDU37 was gradually discontinued. Nevertheless, many e-bikes with this motor are still in circulation.

This tuning tool was specifically developed for the BDU37 motor and allows riders to utilize the full power of the e-bike.

Common e-bike models with Bosch Gen4 drives:

The BDU37 (Bosch Gen4) drive is found in a variety of e-mountain bikes from renowned manufacturers. Examples include:

-Cube Reaction Hybrid Series: This series combines sporty design with the power of the BDU37 and is ideal for challenging trails. Please note: Not all Cube Reaction Hybrid e-bikes are equipped with a BDU37 drive (Gen 4); newer models are more likely to use the BDU38 (Gen 5).

-Bulls Copperhead Evo: Known for their robustness, these models offer a dynamic riding experience when combined with the BDU37. Before ordering this tuning tool, check whether your bike is actually equipped with a BDU37 or a newer BDU38 drivetrain.

-Scott Aspect eRIDE: These e-mountain bikes are characterized by their easy handling and BDU37 support, making them ideal for both beginners and advanced riders. Please also check whether the drive system is actually a BDU37 or a BDU38.

 Important: Even if your vehicle is equipped with a BDU37 drive, this tuning chip is only compatible if the bike has a rim magnet (and no ABS or ABS Pro).

RimBoost scope of delivery

The scope of delivery includes not only the RimBoost chip and connectors, but also an additional spoke magnet and the necessary installation material (cable ties, adhesive tape, etc.).

-1 RimBoost V2.37 chip
-1 Operating Instructions 
-4 cable ties
-1 spoke magnet

Please keep in mind: Depending on the model, you may also need a suitable screwdriver to open the motor compartment (Torx, Allen, etc.) and a crank puller to remove the crank. This depends on the motor cover of your e-bike.

Tip: Bosch Smart System E-Bikes (BES3) can be easily identified by the plug on the charging cable.

SQUARE plug = Bosch Smart System BES3 (Gen4) + Bosch Gen5:

ROUND plug = Bosch Gen2, Gen3 & Gen4:

Does your Bosch E-Bike charging cable have a square plug (as shown above), you have the correct Tuning module selected (provided it is a Gen4 (BDU37) e-bike with a rim magnet, and not a standard magnet or ABS / ABS Pro). If your Bosch e-bike does not have either of these connectors, you either do NOT own a Bosch e-bike, or you own an e-bike with the old Classic Line Drive (Gen1).