In reply to Cookie (North East Wales MC):
Nothing will stop a thief. They will hacksaw through the frame or other part of the bike that is securing it. Steal what is left and ebay the components even if it meant snapping the forks off a bike
Do not under any cirumstances leave a bike unattended even if it is locked on at the forks or with a gold secure lock
If you go to the pub sit where you can see the car. Drive home and if a car is behind you do a loop before stopping outside your house. Put it straight inside the house/shed wherever. Put your strava on private and get a shit old bike for nipping to the shops/pub
Fork mount are also a pita if you have multiple bikes/mates i.e 9m QR,15mm ,20mm or even 22mm axle. You end up having to put filthy wheels in the car.
End of the day go for a rack that is most convenient to use and don't leave the bike alone on the car.