Whether it is on wheels or skis, you can perform various stunts under extreme conditions. Mountainbiking, Skateboarding, Waterskiing; all of these sports fall under this skill instead of Athletics. Even without actual experience in one of these sports, you will pick it up much faster simply by having this skill. Consider it your knowledge of operating and maintaining personal pedal vehicles or other such sports. At the highest levels, you can safely perform incredible-looking stunts.
If combat occurs during this activity, then every 3 or 4 levels in this skill could cancel a combat penalty arising from the activity.