The SX2 dongle – the classic e-bike tuning dongle for Bosch, Yamaha, Shimano, Panasonic, Impulse, Brose & Specialized
The SX2 dongle is a classic dongle solution for e-bike tuning and has been on the market for many years. Its basic principle remains attractive: a compact, pluggable solution that removes the speed limit of many e-bike systems – and can be removed again in seconds if needed.
What makes the SX2 dongle stand out
The SX2 is not a permanently installed tuning module, but a classic pluggable dongle . This is precisely what makes the system so easy to use: dongle plugged in = tuning active, dongle unplugged = tuning deactivated. This clear logic is one of the reasons why the SX2 has been perceived as a proven classic for years.
The SX2 dongle is one of the more established tuning solutions for e-bikes and pedelecs. It is simply connected in parallel to the speed sensor and thereby removes the factory-set speed limit.
This solution is particularly interesting for riders who don't want a permanently installed module. As a dongle, the SX2 can be removed at any time within seconds, instantly returning the bicycle to its original factory condition.
Support is provided for numerous engine platforms, in particular Bosch, Yamaha , Shimano,
Panasonic, Impulse, Brose and
Specialized Turbo Levo.
The major practical advantage
The SX2 is a pluggable solution. This means: dongle connected = tuning active , dongle disconnected = tuning deactivated . This very simplicity remains the core of the SX2 logic to this day.
The operating principle is deliberately kept simple. After connecting the dongle, the speed signal is modified so that the displayed speed is only half as high above a certain range. This bypasses the factory-set speed limit of the e-bike.
In practice this means:
With active tuning, the display only shows approximately the half the actual speed.
This removes the factory-set limitation.
All normal riding modes of the e-bike are retained.
The SX2 dongle is housed in a compact 3,5 mm jack plug . No separate battery is required. Likewise, there is no direct interference with the actual motor electronics. This makes the solution technically straightforward and easy to understand for many users.
The electronics are potted and therefore basically designed for outdoor use.
Important notice regarding the display
With the SX2, the partially displayed screen is not a defect, but rather part of its operating principle. Therefore, anyone driving with an active dongle must be aware that the speed shown on the display does not correspond to the actual speed driven.
Especially with older, classic solutions like the SX2, exact system compatibility is crucial. This applies particularly to Bosch.
Important Bosch notice
The SX2 solution for Bosch from 2014 onwards is Not compatible with Bosch 2020
and also Not compatible with firmware 1.8.4.0 or higher.. Also expressly excluded is the Bosch Smart System.
This is important because many users only vaguely perceive Bosch systems as "Bosch". However, with the SX2, a clear distinction must be made between older Bosch platforms and newer Bosch generations.
For certain Bosch and Yamaha models, there are SX2 versions with an active switch . This allows the dongle to be not only mechanically connected or disconnected, but also to be switched on or off via the light switch .
This is particularly useful for drivers who want a slightly more comfortable user experience without abandoning the basic idea of the classic dongle.
SX2 dongle with activation switch and cable kit for Bosch or Yamaha
classic dongle logic plus an additional user interface
The active switch versions thus extend the classic dongle logic by adding an additional control level, but at their core remain simple pluggable SX2 solutions.
If problems occur during installation – troubleshooting
Even with a relatively simple dongle like the SX2, problems can occur during the initial installation. It is particularly important to proceed systematically and not just focus on the dongle itself.
Are the wires connected correctly, and were the crimp terminals properly crimped or the cables cleanly soldered?
Was the voltage measured correctly according to the instructions?
Was the current also checked correctly, and not just the voltage?
Was the switching behavior of the dongle tested, for example by jacking up the bicycle and rotating it to higher speed ranges?
Was the position of the magnet on the spoke checked and, if necessary, adjusted a few millimeters inwards or outwards?
The last point is particularly important: A magnet that is not optimally positioned can create the impression that the dongle is not working properly, even though the actual problem lies only in the sensor/magnet position.
If support becomes necessary
For a meaningful error analysis, the following information should be sent along with the error message if possible:
The SX2 system also includes individual cable sets and accessories. This is practical if an existing dongle needs to be reused or a suitable connection needs to be retrofitted.
Why the SX2 dongle remains important despite more modern systems
The SX2 dongle is not a new high-end system with an app, Bluetooth, or special smart system logic. But that's precisely where its significance lies: it represents the classic, robust, and easy-to-understand dongle philosophy in e-bike tuning.
The SX2 remains interesting for many older or established engine platforms because it combines three things very consistently:
simple functionality
pluggable reversibility
no direct intervention in the engine electronics
For those who are not looking for an app, a menu system, or highly specified smart system tuning, but rather a classic dongle for proven platforms, the SX2 remains one of the most traditional solutions on the market.
The same applies to the SX2: Active tuning changes the vehicle's legal classification. Usage, responsibility, liability, and legality must always be checked independently.
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