Sitting in a car [or spacerhip or robot cockpit] is awesome in VR because our real bodies are emulating position of in-game bodies [sitting, feets at pedals, hands at wheel/gamepad]. Whenever that happens, the presence is easily achieved [that's why Vive is so good, it does not "break rules of reality" with its large tracking area].
On the other hand, DC bikes in VR will most surely be vomit-inducing [in first person]. All that swaying left and right will wreck our brains since our bodies are standing/sitting still. With third person camera [floating in the air few meters behind the bike], experience could be much better.
Studies/anecdotal experiences have shown that giving VR user "anchor" points can greatly reduce the discomfort. So for example, in stead of us being "ghosts" that are chasing the bike in front of us, user can feel easier if he is placed on solid levitating platform that is clearly visible when speeding fast.
