During rehearsals, the actors are skating on their roller skates for up to 10 hours. Skate mechanics ensure that the skate shoes fit like a glove. Each roller skate consists of 146 separate parts and are fitted individually. During the show, the mechanics are on duty behind the scenes to replace wheels, toe stops, heel brakes, and axels with lightening speed. The pyrotechnic effects, e.g., Greaseball’s roller skates, are controlled by the mechanics and ignited by remote control.