Then comes the heat treatment step, which is also carried out in our workshop. This is a decisive step in the manufacturing process because it gives aluminum its ultimate strength. The frames, after being welded, are heated in an oven at 520°C for one hour and then immersed in water, this is the quenching step or T4. This will be used to normalize the internal stresses after welding. It is also after this step that the alignment of the frames is checked and corrected on a specific assembly.

They are then heated a second time at 190°C for 2 hours to reach maximum resistance. At this stage, called T6, the frames become so tough that they cannot be corrected for faults. The advantage of aluminum is that a defective frame can be recycled and therefore is not a loss in itself.

Some manipulations are still done by hand on these frames such as the threads or the bore of the seat tube. Performing these operations last ensures that these surfaces will no longer move in order to have the best possible precision.