Is a single session sufficient to identify the ideal tyre pressure for the race?

This is untrue: you need more time! Firstly, because the track has to be cleaned and rubberised, then because you need to establish the optimal set-up of the chassis, which in turn influences the tyre pressure. When we talk about competitions at an international level, I would say that we can begin to identify tyre pressures reliably following the second day of testing.

Let’s begin by saying that, often, for reasons related to the possibility of unifying production, some manufacturers use the same frame for both non-shifter and shifter classes, although different set-ups are used out on the track, of course. Normally, however, it is more efficient to produce a KZ frame that is specifically designed to make the most of the powerful 125 shifter engine, which requires more traction and a different chassis flex compared to non-shifter engines. Some manufacturers achieve the objective using tubes with different mechanical characteristics, while others modify the shape of the frame, using a different wheelbase, a greater caster angle, a rear crossbar fitted further back, etc.