[Philip Lelyveld comment: people sweat profusely if they are serious about exercising. I don't know if wearing an HMD, where you can't wipe your eyes, will work in this implementation.]
A series of sensors attach to various parts of the machine: One on the back wheel measures your speed, while another on the front wheel responds to your direction.
Right now, the seven-person team (mostly engineers) is focused on introducing more gamified elements—the kinds of features that will inspire users to cycle faster in order to earn points and ascend to new levels. The idea is to make the VR experience different every time you strap on the headset. That way, you’re far more likely to get back on the bike, making physical activity a subconscious habit.
See the full story here: http://bostinno.streetwise.co/2015/05/18/virzoom-exercise-bike-virtual-reality-game-for-oculus-rift/