What has the skeleton of a German bicycle company and the heart of a Mazda RX-7? It’s a Hercules W-2000, the world’s first Wankel rotary-powered motorcycle.

You can tell it’s unique by the low-slung engine with a large axial fan up front. In an unusual gap between the engine and fuel tank sits the carburetor, which feeds the air-fuel mixture into a quirky but theoretically magical power plant.

What Makes a Wankel Rotary So Special?

Image via Flickr by bufalu

When you think about it, a piston engine is awkward and inefficient. So many moving parts pop up and down to turn linear motion into circular motion. Each piston starts and stops completely with every stroke. German engineer Felix Wankel thought there must be a better way.

He developed a motor designed around an eccentric shaft and a triangular gear. Intake, compression, ignition, combustion, and exhaust worked together seamlessly to spin the shaft at higher revolutions per minute with less vibration and wasted motion. Rather than hopping up and down to create a turning force, Wankel’s engine just wanted to spin.

The Hercules Bicycle Company

In 1886, German company Hercules set forth to put affordable bicycles in the hands of regular people. After the turn of the century, it got into motorized two-wheelers. Typically it built the frames and incorporated engines from other companies, including Fichtel and Sachs. That company, which was one of the first and biggest adopters of Wankel’s invention, purchased Hercules in the 1960s.

With the frame and engine builders united, Hercules mated the rotary to the motorcycle. The W-2000 was born. It hit the market in 1974, featuring an air-cooled 294 cubic centimeter Wankel rotary. Its 32 horsepower and 24.5 pound-feet of torque pushed it to a top speed of 90 miles per hour. Power was distributed through a wet-clutch six-speed transmission and a chain drive.

The big axial fan up front helped cool the high temperature of the rotary motor, especially at idle. The exhaust note, which began like an outboard boat motor but quickly climbed to the song of a roaring chainsaw, was like no other.

How Does It Ride?

Image via Flickr by Hugo-90

Its low-slung engine both aided and hindered the handling. The bike had a low center of gravity and excellent balance, yet the scant 6.5 inches of ground clearance was no good on bumpy roads and prevented aggressive cornering.

The tips of the eccentric shaft on the W-2000 were prone to flutter and break over 6,200 rpm. Buyers were sternly warned to respect that threshold. The transmission, however, would often miss shifts, resulting in unexpected redlines. Accidental over-revving could quickly lead to a costly rebuild. The W-2000 was originally priced at $1,900. You could buy more exciting and reliable bikes for less. Hercules’ project went down in history as a lovable and unique oddball.

The rotary motorcycle was not dead, though. The creativity of Hercules’ engineers inspired others, leading to the Suzuki RE5 later in the 1970s and multiple Norton bikes in the ’80s and ’90s. The W-2000 wasn’t sporty, practical or reliable, but it was special and it opened the minds of future motorcycle designers.

A Rotary Motorcycle? It Was Real

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