Leaning – in the parlance of physics, a shifting of the center of gravity – is an elegant way to turn a bike or motorcycle, though one that comes at the expense of stability and traction. But when the number of wheels exceeds two, lean is something that gets engineered away. Most leaning vehicles – like the three-wheeled Toyota i-Road – achieve balance through arrays of sensors and gyroscopes coupled with electric motors and hydraulic actuators.

The E-Spider achieves its lean through straight-up physics. The cockpit is suspended within the frame at points well above the driver’s center of mass. Rounding curves, that mass naturally swings outward, and a simple linkage causes the wheels to lean in the same direction, like two motorcycles riding side-by-side through a turn.

That’s stable and fun on a road, but the technology really shines when the Swincar ventures off-road. The same mechanism that allows lean in the turn means that when riding across a slope, the wheels are perfectly parallel to the angle of the cockpit, which is, of course, hanging down. The driver’s center of mass stays between the wheels and below the hubs, making the Swincar able to travel up and down 70% grades and across grades of 50%, and its long, individually articulated legs keep all four wheels on the ground.

Each of those wheels is driven by an in-hub, 1000-watt brushless electric motor that delivers big torque and charges during braking, making four-hour jaunts possible even over mountainous terrain. Steering (to start the lean) happens through a conventional steering wheel that turns front and rear wheels in opposition, and throttle and brakes are controlled either on-yoke or via foot pedals.

Inventor Pascal Rambaud spent a lot of time on the Swincar – YouTube videos of earlier builds are worth seeking out – and he seems to have accomplished the holy grail of ATVs: Stable, nimble, and almost completely silent, except for the excited whoops of the drivers.

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