KZ & KZ2: The Gearbox Classes

Ask a karting paddock who the fastest drivers in the sport are and you will not hear about teenagers on their way to car racing. You will hear about the gearbox men. KZ is karting's queen class — the category where careers are spent rather than passed through.

Where it came from

Shifter karting joined the international stage in 1974, when Formula C became the first gearbox class at the European Championship. From 1983 to 2000 FC was contested at World Championship level, before a restructure in 2002 replaced it with Super-ICC — and demoted the gearbox crown to World Cup status. The 125cc Intercontinental C formula soldiered on under that name until January 2007, when the CIK-FIA rebranded the category as KZ1 and KZ2. The final correction came in 2013: KZ1 became simply KZ, and full World Championship status was restored to the gearbox class.

How it evolved

The technical recipe has been remarkably stable: a 125cc water-cooled two-stroke, six-speed sequential gearbox, manual clutch, 30mm carburettor and hydraulic brakes on both axles — around 52hp pushing a 170kg minimum (175kg in KZ2). KZ and KZ2 share that specification; the difference is that chassis and brake homologation is open in KZ, making it the pure factory-prototype class, while KZ2 is the production category where drivers aged 15 and up race homologated equipment in enormous numbers across Europe and the USA. Physically, nothing else in karting compares: braking with 50-plus horsepower behind you, shifting six times a lap per straight, no power steering, no suspension. Gearbox specialists tend to stay for decades rather than seasons.

The honours list is the best in karting. Gianluca Beggio holds the record with five gearbox world titles. Marco Ardigò took three world-level crowns (2007, 2008, 2014). Paolo De Conto went back to back in 2016 and 2017. And in 2013 a 15-year-old named Max Verstappen won the KZ World Championship — he remains the only driver to hold both a CIK-FIA gearbox world title and a Formula One world title. A 2024 switch to mandatory Dunlop tyres at international level stirred protest from teams, proof that in KZ, equipment details are taken personally.

The class today

KZ decides its World Championship in a single knockout weekend, while KZ2 fills the biggest gearbox grids in the sport — including a British Championship run to CIK regulations since 2019. It is also the platform for karting's wildest cousin: the long-circuit superkarts take the shifter concept to 250cc and full aerodynamic bodywork. And unlike the direct-drive ladder, KZ is a destination rather than a stepping stone — its champions are karting careerists, not passers-through, which is precisely why insiders rate the class so highly.

We rank both tiers continuously. See who currently rules the queen class in our KZ world rankings, and track the deepest fields in the sport in the KZ2 rankings.