Look for "Flying 200M" times and average speeds. These are the times/speeds the rider traveled the last 200M of the event.
The current world record is 9.572" held by Kevin Sireau (FR).
This means that he traveled 200M is 9.572". His average speed was
75.22KPH or 46.74MPH. This was the
average speed of the run. I would guess that he hit a peak speed around 48 or 49mph.
Here is a terrible amateur video of the record:
Here is a better example of a previous world record setting run by Theo Bos (NED)