I have not witnessed a chute on a bike rider deploy---but I have witnessed a 2 driver dismounts on drag boats---one with and one without a personal chute---he is the one that was able to walk around drinking beer and recounting the wild ride---the other left by ambulance with severe injuries and several broken bones from the tumble and digging in--vs. the prone linear "sudden stopping" more or less on top of the water.
http://www.youtube.com/watch?v=4vT5MSWi9GUEarly in this video (Waco, 1989) is good footage of deployment of an aerodynamic decelerator on a drag boat driver.
The chute keeps the driver stable after hitting the water, preventing tumbling.
Below is a link to a video of a Top Fuel bike rider getting blown off his bike at 200+ mph.
http://www.youtube.com/watch?v=FeRXI0XRNaI&feature=relatedBelow another video of another Top Fuel bike rider getting blown off his bike.
http://www.youtube.com/watch?v=USwwuonAKpY