This rack can be mounted safely on the outboard side of the towers because of the Viper’s fang that prohibits the carrier from being moved when the skewer is engagedin the rack.  This means that someone can't come up and slide your bike rack right off your bars if mounted outside the towers.  On the other hand, if mounted inside the towers it can be setup to easily move from side to side to make room for a boat or a maybe a new cargo box.
This rack has a newly impoved beautiful solid-steel throw skewer that securely carries any type of fork design.