1921 Henderson Model K (Motorcycle)
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Henderson was one of the most important early American motorcycle manufacturers. Brothers Tom and William Henderson founded the company in Detroit in 1912. Tom had previously worked for Winton cars, and William served as the designer.
All Hendersons were in-line four-cylinder designs, and early models were notable for their long cylindrical gas tanks between two horizontal tubes and their extended frames with an alloy footplate ahead of the engine itself. On this were two pedals, either of which operated the solitary rear brake. Interestingly, the two-seater model actually placed the passenger in front of the driver.
The first Henderson engines were 965 cc F-head designs, with overhead inlet and side exhaust valves. The engine had three main bearings, splash lubrication and a side hand-crank for starting. Timing gears were easily accessible in front, and ignition was by Bosch magneto. The clutch at the rear was connected to the chain via bevel gear.
Carl Clancy was the first motorcyclist to ride around the world in 1912. His Henderson is the only 1912 model known to exist, in a museum in Iowa. In 1913, the company moved the pillion behind the rider and increased the engine to 1,064 cc, while the round tank became flat-sided. Henderson’s 1914 models offered a Thor two-speed rear hub, and full-pressure lubrication came in 1916. For 1917, Henderson added a three-speed gearbox and trailing-link front forks.
In 1917, Schwinn bought Henderson and the company therefore became part of the Excelsior empire. The side-valve Model K was introduced in 1920 and would continue to the end of Henderson production. Leading link forks were adopted in 1928, and a five-main bearing F-head engine in 1929, when the model K was divided into KJ standard and KL super sports. Motorcycle production halted in 1931 and Schwinn went back to bicycles.
The Hendersons, meanwhile, had started building the new Ace four-cylinder motorcycle in 1919, seeking a lighter and faster design. The F-head engine was now 1,220 cc, in unit with a three-speed hand-shift gearbox. Lubrication was by pressure and splash systems, and the finished bikes were painted dark blue. Cannonball Baker halved his 1912 Coast-to-coast Indian record on a 1922 Ace in 6 days 22 hours, 52 minutes, but William Henderson was sadly killed later that year testing a new model.
Arthur Lemon took the company’s helm and a new slim-line model was introduced in 1923, setting a number of speed records – 129 mph from a solo, and 106 mph with a sidecar. Financial problems dogged the company, however, and Ace production stopped in 1924, restarted a couple of times, then was sold to Indian in 1927. Indian adapted the Ace to its own lineup and persevered with the four-cylinder design for another 15 years to the dismay of its V-twin loyalists.