Clutch system for a bicycle transmission

A clutch system for a bicycle transmission having an input and an output, the clutch system including:

• a first clutch unit connectable to the input or output, including a first abutment surface;
• a second clutch unit connectable to the output or input, including a gripping member having a second abutment surface arranged for selectively engaging the first abutment surface, the first and second abutment surfaces being adapted to each other so as to allow disengaging under load;
• a third clutch unit including a retaining member, the third clutch unit being arranged for selectively being in a first position or a second position relative to the second clutch unit, wherein the retaining member in the first position locks the second abutment surface in engagement with the first abutment surface for rotationally coupling the second clutch unit to the first clutch unit, and in the second position releases the second abutment surface for disengagement of the first abutment surface for decoupling the second clutch unit from the first clutch unit;
• and
• wherein a rolling-contact is provided between the retaining member and the gripping member.