Racing Series

Thomas nepveu in three professional series in 2021

SKUSA

(Superkarts usa) in the x30 s (senior) class, the quickest machines in the series

The Birel Art X30 S kart class raced by Thomas Nepveu features a race-bred 2-stroke engine displacing 125 cc that delivers its 35 hp directly from the engine to the rear axle via a simple fixed-ratio chain (Called "direct-drive"). It uses a single brake disc mounted on the rear axle. 

Thomas Nepveu's performance over the years has confirmed his mastery over these super quick machines, and he starts every race with a good shot at the win or at least a top-5 finish. With over 300 races over his career so far, mainly in the X30 S class, Thomas Nepveu has won consistently and finished a great portion of them on the podium, in Canada and around the world. 

The direct drive used by the X30 S class machines calls a specific cornering technique: a constant almost round trajectory to keep the speed as high as possible throughout the corner and the engine within its optimal power range (7,000 to 13,000 rpm) so it can provide the best possible acceleration out of the corners.

ROK Cup USA 

The Birel Art 'Shifter ROK' go-kart used by Thomas Nepveu, the quickest class in the ROK Cup series, differs from a direct-drive machine by adding a six-speed gearbox and a steering wheel-mounted manual clutch to transmit its 45 hp to the rear axle, two brake discs at the front in addition to the rear disc, and an adjustment for front/rear braking distribution.

The cornering technique calls for hard braking and downshifts almost in a straight line on corner entry, snapping the machine to change its direction at the corner apex and hard acceleration out of the corner, in as much of a straight line as possible to avoid wasting power by spinning the rear wheels, and always keeping the engine in its narrow optimal rpm bracket, from 12,000 to 13,700 rpm.

Different race set-up techniques

Setting up and driving a USF2000 is similar to other lower classes with enough power to show standard behaviour traits. It differs greatly from the kart various techniques developed to a very fine point by Thomas Nepveu so far in his career. 

Karts may look simple at first glance with their lack of conventional suspension, but they are in reality very complex to set up for a professional event. In order to obtain the ideal behaviour of an X30 S or Shifter machine on a given track, the team must work to achieve the most effective compromise between flexibility and stiffness of the whole package. 

The team fine tunes the machine by changing or adjusting different components: the chassis support crossbar at the front, how tight or relaxed the chassis bolts are, the thickness and width of the rear axle, the stiffness of the bucket seat and its brackets, the variable wheelbase, the tire compound and pressures, the ground clearance, the rigidity of the hubs, the carburetor and ignition, the gear ratio of the drive chain, to name a few. 

Shifter karts add complexity to the exercise by adding the determination of ratios in the six-speed gearbox and the setting of the front-rear brake distribution.