A slip-on drive for the mountains

The RELO slip-on drive helps push the pedals when it gets hard for the cyclist. And it fits on every bike, whether mountain or city bike. The drive only provides as much assistance as the cyclist wants. To develop the transmission, the experts from RELO and ebm-papst formed a tandem.


The bicycle drive weighs in at only  3.7  kilograms. The lithium-ion battery contributes 700 grams of that. It has a charging time of 45 minutes. The brushless 250-watt motor weighs 1.3 kilograms and the transmission, which is fixed to the bicycle, weighs 1.7 kilograms.

About RELO

Philipp Nagler had the idea of developing a removable slip-on drive compatible with all bicycles. He began looking into the matter while he was still a university student. With three colleagues, he achieved his goal in the German town of Lauf. Now RELO is based in Nuremberg, where over 30 employees work on ongoing development and production.

  • The bicycle drive has been in development since 2013. RELO has been producing and marketing its ingenious drives since March of this year.
  • The name RELO is derived from that of the German engineer Franz Reuleaux, who did pioneering work in gear theory. The Reuleaux triangle looks like a normal triangle with rounded sides. The RELO experts designed the motor and the battery with this shape so more cells could be integrated.
  • The overall system is designed for long-term flexibility. All future improvements will be compatible with the basic system and do not have to be constantly replaced.

Efficient transmission

The transmission needed to fulfill two main requirements: it had to be compact and quiet. With the EtaCrown Wts5 crown gearhead from ebm-papst ZEITLAUF, the drive runs quietly and with an efficiency of 91 percent. The transmission was specially tailored to this application.

Perfectly connected

The cyclist selects the desired drive power level with the wireless Bluetooth thumb switch and is well connected with the RELO app that shows the speed, drive power level and battery level on a smartphone. The app also takes care of software updates for the drive.

Fit for off-road and city

A magnesium housing encloses the transmission, making it both light and rugged. Whether the cyclist charges over rocky terrain or just makes the rounds in city traffic, the magnesium housing is maintenance-free and meets all expectations.

Spontaneous decision

Once the transmission is mounted on the bike, it remains permanently attached to the frame. The motor and battery can be removed in no time and carried in a backpack. The cyclist can decide on a whim whether to ride with or without the drive.

Required fields: Comment, Name & Mail (Mail will not be published). Please also take note of our Privacy protection.

Additional product information can be found here:


Extremely compact and powerful