RimBoost V2.38: for Bosch BES3 with rim magnet (BDU38)

RimBoost V2.38: Chip for Bosch Smart System (BDU38) with rim magnet

Removal of the speed limit of Bosch Gen5 Smart System E-bikes with rim magnets!

This is the first working tuning solution for Bosch Smart System E-Bikes with rim magnet (Rim Magnet), here in a completely revised new edition especially for Bosch Gen5 Engines with the technical designation "BDU38" ("Bosch Drive Unit with serial number 38").

Within the Bosch Gen5 it is Bosch Smart System E-Bikes with the revised "Performance Line CX" drive, which first came onto the market in late 2024 / early 2025. These models are clearly identifiable by the internal designation "BDU38" - it's best to check your e-bike's data sheet or the manufacturer's website for the exact designation of your drive. Please note that this tuning tool is only compatible with Bosch Gen5 e-bikes with rim magnets (but NOT with models with ABS / ABS Pro).

(Note: If you have an older model with Bosch Smart System drive from 2020 and rim magnet as well as the internal marking "BDU37", please select the RimBoost V2.37.)

In contrast to the first RimBoost version, this technically much overhauled new edition is a comprehensive update with all current Bosch Smart System firmware variants are compatible. The module is compatible with the Bosch update 16.19.0 from July 2025 (100 Nm update), and even up to 17.16.0.

Attention: We strongly advise against downloading new Bosch motor firmware – there is NO guarantee that future firmware versions will not be incompatible with the RimBoost V2. Please note that the warranty for RimBoost products does not cover malfunctions caused by updating the motor!

Please also note that installing the RimBoost V2.38 tuning kit is not easy and requires some technical skill. Keep this in mind before you decide to order this product.

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 V2.38

With the RimBoost V2.38 tuning chip, the 25km/h speed limit of e-bikes with Bosch Smart System Gen5 motors and rim magnets are completely disabled (assuming the bikes don't have ABS or ABS Pro). By unlocking them, speeds of up to 42 km/h with full motor support can be reached – of course, always dependent on external factors such as rider weight and payload, gradient, wind conditions, tire pressure, etc.

No Bosch tuning detection

To ensure that the notorious Bosch Anti-Tuning software does not affect this tuning product, extensive test drives were carried out. not applicable Tuning detection by the Bosch system; and there were also no error messages generated. To the best of my knowledge, RimBoost V2.38 appears to be immune to all current anti-tuning measures.

But please note: There are now indications that the infamous Bosch error message "524001" can occasionally occur even without tuning. Therefore, we cannot offer a 100 percent guarantee that this error message will not occur. However, it did not occur during any of our test drives. Nevertheless, we cannot completely rule out the occurrence of a 524001 error. 

A high-quality product from tuning professionals

Behind the RimBoost V2.38 are the absolute tuning specialists from “MountainTuning“ Team. This successful development team can look back on many years of experience in the field of e-bike tuning. We owe "MountainTuning" many absolute tuning classics for a wide variety of models. In recent years, the development team has used its concentrated expertise to finally create a functioning tuning solution specifically for Bosch Smart Developing a system for e-bikes with rim magnets was a project long considered virtually impossible. But it worked, and with RimBoost, a viable tuning option was available on the market for the first time. With RimBoost V2.38, the tuning chip is now available in a second, technically optimized version. 

Only high-quality components are used in the production of RimBoost chips, ensuring the highest level of quality.

RimBoost V2.38 Chip - Installation

Even though installing the RimBoost tuning chip only requires a few steps, it's not exactly easy and takes some time. Please consider whether you're confident enough to perform the installation yourself before placing an order.

RimBoost is a tuning tool in the form of a chip. In addition to two power cables, the chip also has two additional cables: at the end of one cable is a new sensor, and at the other, an electromagnet. To install the tuning, the engine cover must be briefly removed.

Remove rim magnet and attach new spoke magnet: The original Bosch rim magnet must be removed so that it no longer transmits signals to the original Bosch sensor. The Bosch rim magnet must be replaced with the sensor on the RimBoost chip (this is, by the way, the well-known sensor found on "normal" Bosch e-bikes). without Rim magnet located on the rear wheel swing arm). This allows the supplied spoke magnet to transmit the speed to the sensor.

Attaching the electromagnet: The RimBoost sensor informs the RimBoost chip, which in turn transmits signals to the electromagnet. For this tuning, the electromagnet must be attached to the motor cover with strong double-sided 3M adhesive tape, between the rear wheel and the Bosch sensor located in the engine compartment. You can find the optimal position of the electromagnet on the motor housing with the help of a smart installation routine. The electromagnet is so inconspicuous that it is unnoticeable and does not change the appearance of the e-MTB (see photo). In some cases, the electromagnet can also be installed inside the motor housing. 

Our advice: Simply attach the original Bosch rim magnet to the front wheel. This way, it won't get lost. Since the included spoke magnet is attached to the RimBoost sensor in the spoke, the tuning is visually almost indistinguishable from the original removal system.

The RimBoost chip does not require its own battery, as it is powered by the e-bike battery.

Functionality

Once installed, the RimBoost chip's electromagnet will transmit a modified signal to the original Bosch sensor inside the engine compartment while driving. Thanks to the modified signal, the drivetrain is unlocked, eliminating the 25 km/h speed limit. This allows for much faster driving with full motor assistance.

Important: Due to the above-mentioned functional principle, the display of the Bosch e-bike no no longer display the correct values. The displayed speed, etc., will therefore no longer correspond to the actual values.

Our advice: You can easily view real-world data while on the go by attaching your GPS-enabled phone to the handlebars. E-bike mounts for the handlebars is available in our online shop.  

Remove tuning: Simply replace the magnets!

The tuning can be reversed at any time. You can restore the e-bike to its original condition by removing the new spoke magnet and replacing it with the original Bosch rim magnet. Your e-bike will then function normally – that is, the motor support will end at 25 km/h, and the display will show real values.

Compatibility

The RimBoost V2.38 tuning chip is exclusively compatible with:

-Bosch Gen5 e-bikes with Bosch Smart System (BES3) and with rim magnet (Rim Magnet). Compatible with the latest software and firmware versions.

Compatible up to version 17.16.0, so also kCompatible with Bosch Update 16.19.0 from July 2025 (100 Nm update). Also compatible with all older software versions.

You can recognize Bosch Gen5 e-bikes by the technical marking "BDU38" ("Bosch Drive Unit 38"). The marking should be found in your e-bike's data sheet. By the way: The Bosch Gen5 drive system first came onto the market in late 2024 / early 2025 - older models cannot therefore be Bosch Gen5 e-bikes.

You can identify models with rim magnets by the relatively large magnet or the speed sensor on the rear wheel valve. This image shows a rim magnet:

Important: 

-The tuning chip is NOT compatible with Bosch E-Bikes with ABS or ABS Pro.

-NOT compatible with Bosch motors with the identifier "BDU37". For corresponding models with the identifier BDU37 and rim magnet you need the RimBoost V2.37 (also NOT compatible with ABS / ABS Pro).

A few notes on the Bosch rim magnet: By 2024, practically all Bosch Smart System e-bikes do not yet have a rim magnet, but a magnet on the spoke, also referred to as a "spoke magnet." Numerous tuning options are available for models with spoke magnets. However, many now have Bosch Smart System e-bikes instead have a rim magnet on the rear wheel (especially common on CUBE e-bikes with Bosch drives). The rim magnet records all important riding data and, for the first time, does not require an additional speed sensor. The transmitted data is recorded directly in the motor. For this reason, it was previously not possible to tune Bosch e-bikes with rim magnets (remove the speed limit). The RimBoost Tuning Chip was the first tuning solution for Bosch Smart System e-bikes with rim magnets – especially CUBE e-bikes with rim magnets – can now be effectively unlocked for the first time without triggering the Bosch anti-tuning software. This is already the second generation of RimBoost tuning (V2), which works even more efficiently and is also compatible with the latest Bosch firmware versions.

Our advice: Especially if you have a CUBE e-bike with Bosch Smart System drivetrain, you should definitely check whether your bike has a rim magnet or a spoke magnet before ordering a tuning tool. If it has a rim magnet, the RimBoost V2.38 is the perfect choice (assuming the bike's drivetrain is labeled "BDU38" and isn't equipped with ABS or ABS Pro). Get yours now, as demand for this product is extremely high. 

About the Bosch BDU38 (Gen5) engine

The Bosch BDU38, also known as Performance Line The fifth-generation CX, or "Bosch Gen5," is an advanced e-bike motor specifically designed for demanding e-mountain bikers. It was first launched in late 2024/early 2025, with the official launch taking place in the 2025 model year.

The internal technical designation "BDU38" stands for "Bosch Drive Unit with serial number 38". The predecessor had the designation "BDU37" - please check the data sheet of your e-bike for the exact designation of your drive. If in doubt, you can also research on the website of your e-bike manufacturer or ask your dealer directly. This tuning chip is only compatible with "BDU38" motors - if you have a "BDU37" (Bosch Gen4) e-bike with rim magnet, please select the RimBoost V2.37.

Important information about RimBoost V2.38:

-To use the RimBoost V2.38, a Bosch rim magnet is required, as this is responsible for measuring speed. You can identify a rim magnet in the photo above.

-The RimBoost V2.38 is NOT compatible with e-bikes equipped with Bosch ABS or ABS Pro. Please check before ordering whether your e-bike has one of these features. If your e-bike has ABS or ABS Pro, there is currently NO tuning solution.

Bosch Gen5 e-bikes with BDU38 drive unit:

The BDU38 motor unit can be found in a variety of e-mountain bikes from well-known manufacturers, especially CUBE models. Here are a few examples:

-Cube Stereo Hybrid ONE44 HPC AT 800: This model combines a lightweight carbon frame with the powerful BDU38 motor, ideal for demanding trails.

-Cube Stereo Hybrid ONE22 Race 800: Equipped with the Bosch Performance Line CX motor and an 800 Wh PowerTube battery, this bike offers an impressive range and Performance for versatile trail adventures.

Please note: The e-bikes listed above are only compatible with this tuning if the bikes are equipped with a rim magnet (and not with a spoke magnet or ABS / ABS Pro).

Technical data of the RimBoost V2.38

• Chip box: 3,2cm × 2,8cm × 1,3cm
• Diameter for mounting the magnetic encoder: 2,3 cm (slightly flexible)
• Length of the magnetic encoder: 6,7 cm
• Length of the cable to the magnetic sensor: about 12,5 cm
• Length of the cable for power supply in the Bosch motor (female): about 12 cm
• Length of the cable for power supply in the Bosch motor (male): about 11 cm
• Length of the cable from the box to the chainstay sensor: about 35 cm
• Product weight: about 42 g

RimBoost V2.38 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:

-1 RimBoost V2.38 chip
-1 Operating Instructions
-1 spoke magnet with wing screw
-4 cable ties

Please keep in mind: Depending on the model, you may also need a suitable screwdriver to open the motor cover (Torx, Allen key, 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 the bike has a BDU38 drive unit and no ABS / ABS Pro and a rim magnet instead of a standard magnet). If your Bosch e-bike does not have either of these connectors, you either do NOT have a Bosch e-bike, or you have an e-bike with the old Gen1 drive (Classic Line).