Details of the event,

Round 4 of the American Suzuki/ RacerX/ NAHA Pro Series. Held at the Jackpine Gypsy Club Grounds. Sturgis, South Dakota, August 9/10 2006.

Nearly 40 bikes competed with engine capacities from 800cc right up to 2500cc. Traction was provided in most cases by bolted paddle tyres and chains on the rear, running on Nitro-Methanol-Nitrous, these bikes were putting out, up to, and over 200 hp. Even with all that behind them on the rear wheel, only a very few made it all the way to the top, and, as if the hill was not enough, they were competing against a clock as well.

Spectacular stuff.