As would the saliva from the person in front (as their mouth gets blown open) - if you sit behind the guy in front
There's a lot of things they need to make sure the are OK from a safety perspective first - as this has the potential to end abruptly if they don't cover their backsides well enough.
Thats serious speed - with serious G's. Any more than that and there is the potential to cause some spinal injuries and cerebral problems if the riders aren't harnessed properly or have underlying medical conditions. And if there's a problem - stopping quickly at top speed probably isn't an easy option.