Haibike Bosch Gear Pulley

Hi Rich here from eBike Sussex the Haibike Specialists. You may have noticed a pulley wheel above the front chainring on some of our Haibike Electric Bikes. Well this amazing device is fitted to all of our Full Suspension Bosch powered Haibike. It is Haibike’s patented S.E.S. System. But what does it do? Let me explain…

The Pulley wheel is designed to maintain a normal chain alignment on a full suspension electric mountain bike. This means Haibike have been able to shorten the chain stay on their eMTB and therefore increase the power transfer from chain to sprocket. It is also designed to stop the chain from coming off the front chain ring on bumpier terrain.

This is a replaceable part but cannot be retro fitted to a bike. You need the mounts on the frame that are built into Haibike’s full suspension electric mountain bikes. The jockey wheel was originally designed to ensure the main pivot of the suspension was not positioned within the motor. This would have caused multiple issues, bulkier bikes, motors that would require major re-design from Bosch, longer chainstays and less ground clearance. This is one of the major reasons you will see Haibike’s rival electric mountain bike brands have poor geometry, aesthetics and ergonomics to differing degrees. It is no accident that Haibike are market leaders in design. They have invested time, money and effort into creating a brilliant solution to a design problem.

In Haibike’s own words:

We developed the Sprocket Equalizing System (S.E.S) in order to move the main pivot upwards and achieve the shortest possible wheelbase and a correct axle path. By positioning a pulley wheel directly on this point we can also prevent chain jack and pedal kickback during compression. We also incorporated a chain guide on the pulley wheel. Together with the guide on the Haibike Sprocket a chain drop—even in extreme conditions—is almost impossible.”

I hope this explains the Haibike S.E.S. system and why we believe Haibike to be the best eMountain bike brand in the world.


eBike Sussex

Haibike Electric Bike Specialists