Tilting EV uses counterweights to prevent toppling

Tilting Kairos EV
A rendering of the Kairos EV highlights its Mobile Lateral Element near the front wheel and the Programmed Restraint Device behind the handlebars. Images courtesy SIREMS Association

Tilting electric three-wheelers have gained attention for their agility and fun driving experience. However, their safety compared to traditional four-wheeled vehicles remains a concern. The Kairos EV, a novel three-wheeler, aims to address these safety issues with two innovative systems designed to prevent toppling and enhance overall safety.

Conceived by French transport designer Mathieu L’Hopitault and developed through the SIREMS Association, a French nonprofit group focused on electric mobility, the Kairos EV is currently in its pre-prototype stage. This two-passenger vehicle takes a different approach to three-wheeler design by placing its two wheels at the rear, unlike most three-wheelers which have them in the front.

Unique design for enhanced stability

The rear-wheel layout of the Kairos EV is complemented by a semi-reclined, feet-forward riding position. This configuration places most of the rider’s weight over the rear wheels, which are responsible for delivering all the torque, thereby optimizing traction. The rear wheels of the Kairos also tilt relative to the vehicle’s main body when cornering, allowing the vehicle to lean into turns and enhancing stability.

To further reduce the risk of tipping over during turns, the Kairos features Mobile Lateral Elements (MLEs). These wedge-shaped appendages, located on either side of the front wheel, tilt in conjunction with the rear wheels as the vehicle leans into turns. The MLE on the inside of the turn remains clear of the road surface, while the MLE on the outside acts as a counterweight, helping to prevent the vehicle from tipping.

Tilting Kairos EV Riding Position
This graphic showcases the rider’s position, demonstrating the tilting rear wheels and the Mobile Lateral Elements (MLEs).

In scenarios where the vehicle might still tip, the inside MLE contacts the road, effectively propping up the vehicle and preventing a complete rollover. These MLEs also serve several other functions: they absorb impact energy in frontal and side collisions, boost aerodynamics by diverting airflow around the rear, and help maintain a low center of gravity. Additionally, they provide storage space for cargo, with a larger compartment situated between the rear wheels.

Tilting Kairos EV Main Cargo Compartment
The primary cargo compartment of the Kairos is situated between the rear wheels.

Advanced restraint system

The Kairos EV is equipped with another safety feature known as the Programmed Restraint Device (PRD). This wedge-shaped device is mounted in the cockpit, positioned so that the rider’s chest rests lightly against it. The PRD is hinged at the front and locked electrically at the rear. During a frontal impact, the PRD absorbs much of the inertial energy and acts as a physical barrier to prevent the rider from being thrown over the handlebars.

In the event of a severe impact causing the vehicle to flip forward, the PRD’s locking mechanism disengages, allowing it to pivot forward. This mechanism allows the rider to be thrown clear over the handlebars, but in a more controlled manner than if the PRD were not present.

Tilting Kairos EV PRD
The Programmed Restraint Device (PRD) not only enhances rider safety by absorbing impact energy but also doubles as an additional cargo space.

Development and future prospects

SIREMS Association founder Philippe Girardi has announced plans to have a rolling demonstrator vehicle ready for testing by the end of the first quarter of next year. While specific details on availability and pricing are not yet clear, Girardi aims to have the Kairos EV on the market by 2028, with a target price of no more than €30,000 (approximately US$32,553).

The Kairos EV, with its innovative safety systems, represents a significant step forward in the design of tilting electric three-wheelers. Its unique combination of rear-wheel tilting and Mobile Lateral Elements offers enhanced stability and safety, potentially making it a safer alternative to conventional three-wheelers. As development progresses, the Kairos EV could set new standards for safety and performance in the electric vehicle market.

Source: SIREMS Association