The comments said
Gunstock, which would have made for an interesting "road course". Even I would have liked to see motorcycles navigating a course like that.
It sure beats downtown-Wolfeboro wheelies.
If you want to see some motorcycle "spills" check out the races at Nürburgring's old road course in Germany, where for about $10, you can "run-what-you-brung" over a 12-kilometer course. (Been there twice with Porsche and BMW, for ten days of "seat-time").
Sometimes, oil is spilled, which makes for slippery biking.
Amazing how bikers take a tumble, sprint back to their bike, and start it back up!
https://www.youtube.com/watch?v=3JRbZV5epX4