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Hercules was a brand of bicycle and motorcycle manufactured in Germany.

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The Hercules Company was founded in 1886 to produce bicycles and began producing motorcycles in 1904. It was merged with Zweirad Union after being purchased by ZF Sachs in 1963.

In the 1950s and 1960s Sachs was the largest European fabricator of two-stroke motorcycle engines. Many of these engines were used in the Hercules line of small motorcycles, scooters and mopeds.

In 1974 Hercules became the first company to offer a Wankel-engined motorcycle for sale to the general public. A prototype was first shown in 1970 at the West Cologne Fall Motorcycle Show to a mixed reception, and the production bike was sold as a Hercules product except in the United Kingdom, where it was marketed as a DKW motorcycle. The W-2000 had a single-rotor air-cooled engine of 294cc that produced 23 hp, later increased to 32 hp. Cooling was by a large fan placed in front of the engine (and the slipstream breeze while riding) and engine lubrication was by manually adding oil to the fuel in the tank.

In 1976 Hercules launched the W-2000 Injection in which engine lubrication was from a separate oil tank via a pump. It had 18-inch wheels, a front disc brake and a rear drum brake. According to a March 1976 review in Cycle World, the handling was good but the bike's low ground clearance limited its cornering ability. That review also declared the W-2000 to be a daily commuting bike, not a sport motorcycle.

Hercules introduced a rotary-powered dirt bike (the KC-30 GS Enduro) in May 1975, but the model failed to sell due to its high price ($2,900).

The Fichtel & Sachs single-rotor engine of 300 cc swept-volume as used in the Hercules – the only commercially available engine at the time – was used as a basis by BSA's project engineer David Garside in the early 1970s when designing a twin-rotor motorcycle engine of 588 cc, which reached production as the "Norton Classic".

Production of motorcycles ceased in 1996.

Hercules W-2000: The First Rotary-Powered Motorcycle

Extracts By Greg Williams MotorcycleClassics.com

The Hercules W-2000, the first rotary-powered motorcycle, was developed in the late 1960s based on the Wankel rotary

The Hercules W-2000 is referred to as the first mass-produced Wankel rotary-powered motorcycle. Envisaged in 1919 by German engineer Felix Wankel, the rotary power plant was thought by many to be an ideal engine. The Wankel rotary had far fewer moving parts than a four-stroke engine, and was theoretically more efficient.

But it wasn’t until 1957 that Wankel, working with NSU, built his first running prototype rotary engine. The transportation industry took notice of this new engine; from aircraft manufacturers to automakers to motorcycle builders, everyone seemed interested in the new technology. One of the first to license the Wankel technology was Germany’s Fichtel & Sachs, at that time Europe’s largest producer of two-stroke engines.

In the 1950s, German motorcycle maker Hercules used Sachs lightweight two-stroke engines to power their many different motorcycles, mopeds and scooters. Sachs purchased Hercules in 1963, and eventually merged with the Zweirad Union, which included the DKW brand.

Hercules developed the W-2000 using the Sachs rotary engine in the late 1960s, and a prototype machine was first shown at the 1970 West Cologne Fall Motorcycle Show. 

According to the article, 20,000 of the 294cc Sachs rotary engines found in the prototype W-2000 had already been used in U.S.-produced snowmobiles, and another version of the engine was used for powering small aircraft. In the prototype, Hercules borrowed a 4-speed gearbox and shaft drive from a BMW R27 single.

How the rotary-powered motorcycle works

When Hercules officially launched the W-2000 in 1974 (sold as a DKW in the U.K. because a bicycle manufacturer already had rights to the Hercules name), the BMW gearbox had been replaced with a 6-speed unit with chain final drive sourced from a Penton 400 dirt bike. A set of bevel gears transferred power from the rotary shaft through 90-degrees to the transmission mainshaft, and the clutch was a seven-disc affair running in an oil bath.

What is of primary interest is the Sachs rotary engine, which used a single spark plug firing a single rotor with apex seals.

“The rotor’s tips seal against the housing to form combustion chambers. Instead of a crankshaft, a rotary uses an eccentric shaft with the rotor riding on the eccentric. A stationary gear on the end of the eccentric shaft keys the rotor to the eccentric shaft. Combustion pressure pushes the rotor away from the combustion face, causing the eccentric shaft to rotate. The shaft’s eccentric defines the throw of the rotor while the stationary gear defines the rotor’s position on its axis. As the rotor spins, its axis shifts, causing the rotor to orbit and alter the combustion chamber for intake, compression, ignition and exhaust phases.”

When first introduced, the Sachs engine was rated at 23 horsepower, a figure that was later improved to 32 horsepower. While listed at 294cc, for comparison to a piston engine that figure, in theory, should be multiplied by two for a 588cc capacity: A single-rotor Wankel produces one power stroke every crank revolution, whereas a single-cylinder 4-stroke requires two crankshaft rotations for each power stroke.

Fuel and air are mixed in a 32mm Bing carburetor, and a single exhaust header splits into two under the engine and feeds two mufflers, one on each side. The Hercules W-2000 relies solely on a large axial fan at the front of the engine.

The running gear consists of a tubular steel frame with twin front downtubes that bend back and run over the top of the engine. As a result, the Sachs rotary appears to hang from the frame, although it’s also supported at the rear.

The front forks are Cerianis with 4.5 inches of travel, and the rear swingarm is damped by adjustable preload Ceriani shocks.

The Hercules wears 18-inch wheels at both the front and rear, and the front brake is an 11.8-inch disc, while the rear is a 7-inch drum.

Period tests of the Hercules give the machine credit for its cornering stability, but fault the 6.5-inch ground clearance as a major detractor in its cornering ability.

“If it weren’t for the limited ground clearance,” Cycle World said in its March 1976 review, “handling on the Hercules would far exceed the capabilities of the engine.”

Cycle World said the W-2000 would burble along at an indicated 60mph, and would climb a hill in sixth gear at 50 to 55mph, but said it took at least one and most probably two downshifts to overtake a car on the highway:

“…performance is not spectacular, just adequate if the driver of the car you’re passing doesn’t stand on it at the same time. If he does, you lose,” Cycle World said.

Partial product line

• Hercules K500 1932–1936
• Hercules s125 1939–1943
• Hercules b50 1932–1935
• Hercules Moped, 49cc (1957)
• Hercules Scooter, 50cc
• Hercules Ultra III Sachs 50 SW
• Hercules Lilliput, 98cc
• Hercules MK1 moped
• Hercules MK2 moped
• Hercules MK3 moped
• Hercules MK4 moped
• Hercules supra 4gp moped
• Hercules supra 4 enduro moped
• Hercules Prior Moped
• Hercules Lastboy
• Hercules K100 (1959)
• Hercules R 200 (1959)
• Hercules 220 (1965)
• Hercules 103 (1966)
• Hercules Postie Bike (1969)
• Hercules K 105 X (1970)
• Hercules K 125 X (1971)
• Hercules K 50 RX (1971)
• Hercules K 125 Military (1971–1990)
• Hercules K 125 (1972)
• Hercules K 125 T (1973)
• Hercules K125 S (1974–1979)
• Hercules W-2000 (1974–1978)
• Hercules E1 (1974)
• Hercules KC-30 GS Enduro (1975)
• Hercules 175 GS (1976)
• Hercules GS250 Ice Racer (1977)
• Hercules MC250 (1978)
• Hercules DKW 250 GS (1978)
• Hercules Prima 5S (1984)
• Hercules Prima frisiert
• Hercules GS 125B
• Hercules KJBe
• Hercules K 180 Military (1991–1996)