Have you considered using a remote flash so that it can be positioned out of the line of sight of the riders like someplace slightly off to one side and up high, if possible?
If I HAD to shoot that, then strobes would be my answer, too, although you had better sharpen up your "Get it in one shot" technique. 
Arena Lighting
Pocket Wizard basics and then some! (Part 2)
Plan on one side light & one on camera, minimum. A backlight would be icing on the cake.
Using a continuous light may present a slight logistical problem. Will there be an electrical outlet where you can plug in the light?
Strobes put out much more light per unit of time. And at the distance you'd probably have to shoot, I guess you'd need at least a 2,000 wt focusing spot. Then you'll run into issues like blown fuses, people tripping over the cable...
Not allowed to use flash!!
Then, IMO, you're screwed. I suggest that you get permission to do a test at an event & have the organizers poll the riders after. See my comment here:
https://photography-on-the.net …hp?p=2906448&postcount=42