A brake unit for a safety brake of an elevator system has a rolling element on a rolling disk, which rolling element rolls on a stationary rolling track of a braking and guiding rail at least in some sections in the event of an activation of the safety brake. A brake lining of the brake unit interacts with a stationary braking track on the rail as a result of the rolling of the rolling element on the rolling track. At least one marking element on the rolling element produces a start marking and an end marking on the rolling track and/or the braking track when the rolling element rolls on the rolling track. Then the braking distance of the associated elevator car can be determined from the distance between the start marking and the end marking.