The Radar Drive ships with a variety of straps and adapters to mount to your bike. Select whichever of the two included straps allows for sufficient tension given your seatpost size.
For round seatposts, the strap can just be wrapped around the post and seated fully in each strap hook.
For D-shaped seatposts, or other aero-style seatposts with a thin, flat trailing edge, you can use the D-post adapter.
For airfoil seatposts with a sharp radius or thin trailing edge, you can use the Aero Post adapter.
If you have any questions about mounting your Radar Drive, please submit a request for help.