>Suggestions and Feature Requests>Race Types?
Maybe a category field with default choices of track, road, and trail, and the user could add new ones if desired (e.g., mountain) -- the way that activities and activity types work. If a user wanted to make a new "sprint" category to hide those, they could then do that.
(I may be just echo'ing what Julia said above in a different way.)
Note: Timed races are kind of problematic for PR listings that are sorted by distance.
It's a 5k. It hurt like hell...then I tried to pick it up. The end.