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TKART magazine Under Review | RY30 S12: the Birel ART single-speed chassis
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Max Bernardi
24 February 2021
CIK-FIA 2015 – 2021

The homologation of the RY30-S12 frame dates back to 2015 and is valid for 7 years, until 2021.


The article analyzes the configuration for the single-speed classes.


Generally 30 and 32 mm tubes are used. Either all the same, or mixing them. The RY30 has all 30mm tubes.


There are two "schools of thought": hand-held or robotic. Birel ART, manufacturer of the chassis, welds by robot.


Standard accessories in aluminum. On request, also in magnesium.

The Birel ART RY30 S12 is the 2021 development of the chassis with 30 mm diameter tubes by the company from Lissone. The single-speed kart, relative of the CRY30 S12 model intended for shifter classes, introduces interesting solutions to optimise performance and improve the driving position.

The RY30 is not an absolute Birel ART novelty. The approval of the body in 2015, previously expiring in 2020, was extended until the end of 2021. The extension was wanted by the International Karting Commission to simplify the production and commercial operations of manufacturing companies during the COVID-19 pandemic. Compared to the CRY30 S12 (Shifter) version already analysed by TKART, the Birel ART RY30 S12 (Direct Drive) is not just different because of the lack of a front braking system, gear lever and clutch lever. In fact, at the rear, there are other differences such as the flanges, housings of the bearing support cases, which have four fastening holes, two less than the Shifter version.

This feature makes it less rigid and allows the chassis to be "freed" when cornering, a positive situation to make the most of the lower power of single-speed engines compared to those with gearboxes. Furthermore, the KZ version has 42 mm higher flange bearings to make space for the two extra holes useful for fastening the cases: this allows an increase in the overall rigidity of the chassis structure at the rear, a feature that, on a track, translates into more traction when coming out of bends.
As standard, the Birel ART RY30 S12 is fitted with the KG front spoiler model 506, whose shape was defined using CFD (Computational Fluid Dynamics) software to simulate the impact of air against the kart.
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Above is the flange of the single-speed chassis, with the KZ version below.
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Above, there are four fastening screws for the bearing case in the single speed chassis. In the KZ chassis, below, there are six screws to increase the rigidity of the rear axle.
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The shape of the chassis is also different: if at first glance the body of a single-speed kart looks the same as that of a KZ kart, when you compare them you will notice several differences. The most visible ones are on the curves of the side stringers. In this area, the Birel ART technicians defined the different balances between the two versions: by moving the three curves of the side stringers, those at the height of the fuel tank, the load balance between the rear and the front is defined, making the chassis move in a smoother manner when cornering or more “attached” to the asphalt. The design of the body also takes into account all the other above-mentioned features (the different flanges for housing the bearing carriers, for example), in addition to the different type of tube that is obviously different between the Shifter and Single-speed models.
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