You're filming for a sponsor, no doubt for their marketing in some way ?
If so you are part 107 ?
It's very likely this would be needed for such filming, even if not being directly paid for the work.
You should know the rules for flying over people if holding that commercial drone licence, consider the rules for riders, officials, and spectators.
(Apologies if you do hold part 107, but you didn't mention it.)
You'd very likely need approval from the race organisers too, and they may want licenced and insured etc, particularly public liability insurance.