at least you can check what it is when all riders are going down the hill after each practice run. most of us just coast watching the view. crusing in the middle of 150 bikes at 14000ft is something for sure.
Go Pros are great, and conveniant, but all the accessories are crap. so many vibrations on my bike climbing the hill, that GoPros clamps broke twice, and i was lucky on raceday, some cool peeps gave me my GoPro back when i was coming down after racing. well it sure isn't perfect yet, but they sell so much of those that i'm sure they'll improve soon some better clamping systems. otherwise, i do have some ideas....