Custom: Please tape two pencil under the hind legs and two erasers under the frontlegs of the chair and than start tipping with the chair for and back.

The most of the time you sit fullweight on the hindlegs, the frontlegs are always in the air. From time to time you stand up from the chair to see what happend with the pencils and the erasers, if a pencil breaks in 2 parts under you weight you take one part and tape the half part from the pencil under the hindleg again.