Everything is allowed on the Ring at the same time, bikes, beaters, etc. as it is considered a toll highway. The bikes do come up on you quick sometimes, but in the 6 or 7 laps I did, there were no bikes off the track or involved in incidents. There were several cars stuffed in the wall though, the first one only a couple of corners after I got on the track. The pavement was quite wet for all but a two of my laps. I expect the bikes tend to shy away from those kind of conditions there. I know I would!