For riding in bikepar there is no activity - can understand why.
at least like the skiing activity - do not care about lifts and count on only ways down.
i made my own activity from ski template but there is all the time picture of skier - let us change it or make bikepark activiti instead of others types of biking. From my point of view bikeparks are growing and this should be essential activity instead of fishing.
looking forward to hearing from you,
best regards
MatezZ