The center of rotation on a full suspension bike is typically located behind the chainring (A). This creates a smooth wheel path, minimizes pedal kickback, and stabilizes the chain. This same design creates problems when used with a motor (B); it creates a wheel path that increases pedal kickback and lengthens the wheelbase significantly, causing the bike to stiffen up against obstacles and handle poorly.
Haibike's engineers created the SES (Sprocket Equalizing System)(C), which separates the chain from the chainring by guiding the chain over a pulley wheel that is located directly on the swingarm pivot point. This decreases pedal kickback while preserving a short, sporty wheelbase and quick handling.