The non-gear version of the Tony Kart Racer 401 RR established itself among the bends of the Italian circuit. Historically, the Racer had a body composed of tubes all 30 mm in diameter and made of a specific molybdenum chrome alloy (for further information, “Under examination | Racer 401 RR, the latest evolution of the Tony Kart OK world champion“). It must be said that Tony Kart also has the TDX model in its range, with 32 mm diameter tubes. However, the Tony Kart Racing Team preferred to opt for the Racer 401 RR model, for several reasons: the characteristics of the Naples International Circuit; the type of engines used in the OKJ, which do not release power such as to clearly affect the bending and torsion of the chassis; the XH3 Vega tyres used (option), therefore with a hard compound, and, above all, the physical characteristics of Enzo Tarnvanichkul. During the days of the race, the Thai driver (14 years old), weighed about 45 kg and was 1.60 m tall. Although these characteristics ensure advantages in terms of saving the overall weight of the driver-kart combination (allowing ballast to be added at strategic points in order to reach the minimum weight imposed by the regulations), it must be emphasised that they can also have a negative impact, if not correctly evaluated, on the reactions of the chassis, which, undergoing little load transfer, tends to work in a rather “flat” manner. In fact, in karts, since there are no shock absorbers and differentials, the relationship between the driver’s build and the flexibility of the body is an aspect that must be expertly managed. This is precisely why the choice regarding the second chassis (to be used in wet conditions or for any irreparable damage to the main kart), always fell on a Racer 401 RR with 30 mm diameter tubes. Given these premises, it would not have made sense in the Junior class to evaluate the version with a 32 mm diameter chassis (to have a different chassis option than the relevant kart), which is too rigid for the stresses exerted in these conditions.