The motor cradle is designed to suit a range of frames and is slotted to allow exact alignment of the cog and chainset. Hidden is the chain exit slot (look at the bottom view of the cradle below). The side is bolted on so that a chain can be installed with a breaker. 3 motor positions are provided - 2 axle slots, and the sides can be exchanged for the 3rd position.
A chain tensioner (not shown) also has 3 positions. 2 frame clamps (with plastic grommet and tube to prevent paint damage and provide grip) hold the cradle to the bicycle frame.
U -clamps hold the cradle to the frame. In some cases a torque arm is required from the motor to the frame to prevent rotation of the cradle under full power