One of the things is the rocking and the damage it can do when the bike carrier is mounted in a
RECEIVER .
You need a good anti rattle device so you don't get so much play in the receiver,thus magnifying the movement and doing more damage to the bike carrier.
I have tried almost every Anti Rattle device on the market, most have been no good or so complicated and cumbersome that they are useless. Including the Roadmaster type,totally useless.
Until I found the one at Hitch Rider.
Their
Hitch Vice is the best and easiest one I have come across and it really works.