ECOSSE ES1 SPIRIT

It is a relief when a new motorcycle project is announced whose claims a) are arguably new but do not exist outside physical possibility, and b) are not founded upon T-shirt sales and nostalgia.

A group of English Formula One engineers, together with an American couple, have shown plans for a new sportbike to be called ES1 Spirit. Its design can actually be termed “radical.” When I asked Ecosse’s Don Atchison (the American), “Who’s paying?” he replied, “Friends. For now.”

Engineers Richard Glover, Andy le Fleming and Richard Tyrrell represent a range of motorsports skills. They saw two major areas—weight and frontal area—in which significant advances could be made. Here is a short bill of particulars: 265 pounds, 200-plus horsepower, 50 percent of the drag of modern Superbikes. The plan is to build 10 track-day examples and test public response. As of now, the bike exists only virtually in SolidWorks, a 3D CAD software system, though extensive FEA and CFD computer analyses have been performed.

The light weight—100 pounds less than current 1000cc sportbikes—comes from “deleting the chassis.” Some savings come from the literal lack of a frame. Swingarm and rear suspension attach to the gearbox, and front suspension to the engine. More comes from eliminating the weight associated with transmitting front-wheel forces up a slender fork through a steering-head then back down to the rest of the machine. The front suspension consists of twin A-arms, projecting forward, their apices defining a steer axis and carrying an upright from which projects the front-wheel spindle. The lower A-arm is, in effect, a single-sided swingarm. To avoid the “muddy” steering feel of earlier articulated front ends, the handlebars are on the upward-projected steer axis, their motions so defined that resulting feel will be like that of the familiar direct-steering telescopic fork.

Entirely missing is the friction of umpteen spherical joints.The engine will be a “bespoke” (made for the application) transverse inline-Four, integrated into this design. When I asked Richard Glover for details of the engine, he replied, “It is a chassis project.” This is wise. The more ambitious the revolution, the more numerous the failure modes become.

And how is drag to be reduced? Current-day designs set the rider as high as necessary to keep wide-spaced footpegs off the ground. Footpeg width is set by swingarm structure and the amount by which the drive chain is offset from the bike’s centerline. The Ecosse group has rearranged components to narrow the rider across the knees and lower the seating position, said to cut frontal area 28 percent. A major element in this is to send power up the centerline to a transfer shaft at the top of the swingarm, then by a second, offset chain, down to the wheel sprocket.

ES1 is therefore a design based upon adapting the machine to the rider, rather than the other way around. Predictive analysis has reached a high level in F-1, and Ecosse’s studies say this project will work as claimed. We hope to see a prototype under test soon.

Sound off! Pipe dream or in the pipeline? What’s your take on the Ecosse ES1 sportbike?