Used Yakima Bike Mount.

Conveniently transports your bike without the hassle of removing a wheel; folds down when not in use. Fits a wide variety of bicycle down tube shapes and sizes between 1"- 3" in diameter; disc brake and thru axle compatible
soft, padded claws cradle bike tubes without harming paint finish.

Includes two universal mounting brackets (52 in. long) that allow the brackets to fit round, square, and most factory crossbar rack systems. Also includes two frame holders and three wheel straps. (Note there should be four. You can buy replacement wheel straps for roughly $15).

This mount looks very similar to the second picture above.