Abstract: The present invention relates to an electric drive system for a bike comprising a portable electric friction drive device and a bike bracket. A first drive device attachment point is located at a rear part of the friction drive device. A second drive device attachment point is located between the front part of the friction drive device and the rear part of the friction drive device. An inclination control arrangement is configured to control the inclination of the imaginary line between the second drive device attachment point and a contact point of the drive wheel by adjusting the tilt of the friction drive device over the second drive device attachment point. The bike has at least one wheel, comprising the electric drive system, wherein the drive wheel is arranged to be contactable to the tire of said wheel at said contact point.