I have had a GPS in my pocket and find the max speed in the 20 MPH range most of the time. I tend to fly a bit fast on the loop as well. My personal record is 45MPH. That was stupid fast considering how the steering on a trials bike is not set up to do anything close to that. The owners manual published a top speed rating of 99 kmh or 61 MPH, which I don't see any way anyone could actually pull that off.
I have friends who ride mountain bikes faster then I cruise the loop over similer terrain. Realisticly loop speeds are in the 10-15 MPH range unless there is something that begs to be ridden faster.