Door closer

This device was originally designed with a spiral spring as an actuator (attached stl file).
However, given the visco-elastic characteristics of PLA, this spring loses its effectiveness very quickly.
It took looking for another type of actuator and opted for the use of bicycle inner tubes.

A piece of inner tube (700x20 to 23mm for road or racing bike) of about 900mm in length allows the spring to be made.

This inner tube is installed in double thickness in the system. The two ends are fixed in the hub and the central fold on the training cleat. The winding is done in a spiral on the rollers (see photos). To prevent residual air build-up, a hole must be drilled in the central part of the air chamber.

Fixing is done by creating a loop which is inserted into the housing and then a stopper is placed in this loop.

The tension can be adjusted by varying the length of the inner tube and the offset of the arms. The travel takes place at an angle of about 120 °.

The design of t