Judging by aerials it's a pump track and bicycles are the main way to use them (you can "pump" with your weight instead of pedaling)

https://en.wikipedia.org/wiki/Pump_track

cycling=pump_track seems to be used 313 times, don't see the reason to remove it. 
sport=cycling suited this better too than skateboards, though both can be present. 

Maybe someday I'll try to change pump tracks in Estonia to somewhat similar tagging. (my last change to track just added some tags)
