Ace was founded in 1919 by William G. Henderson – an American engineer and motorcycle designer who had previously founded Henderson Motorcycle, which he had sold to Ignaz Schwinn’s Excelsior Motor Manufacturing & Supply Company in 1917.

William carried on working at Excelsior for just under 2 years before differences in opinion resulted in him resigning and deciding to go it alone once again – this time with significant personal wealth from the sale of his first motorcycle marque. His new company would be called the Ace Motor Corporation and it would use a newly designed inline-4 that was similar to Henderson’s previous engine designs – but carefully avoided any patent infringements.

The new Ace motorcycle was known as the Two-Wheeled Duesenberg due to its performance ability and exceptional engineering. In order to drum up interest in the new motorcycle the new company recruited Erwin G Baker out from under the nose of Indian for a “cannonball run” across the United States. Erwin set a new transcontinental record on his Ace of 6 days, 22 hours, 52 minutes, – smashing the then current record that had been set on a Henderson – also designed by William.

The new Ace Four engine utilized and F-head (inlet over exhaust) with very similar valve gear to the original Henderson design, with a swept capacity of 1220cc the engine can produce 16hp at the rear wheel and is rumoured to be capable of 75mph in the right hands – although you’d need to be a brave individual to manage that. The Ace uses a chain final drive, after power has passed through the 3-speed hand-shift transmission

Tragically, William Henderson was killed in a collision with a car in 1922 while testing the Ace Sporting Solo in Philadelphia. He was just 39 years old, and his death was an ultimately fatal blow to his company too – which struggled on for 2 years before being eventually being bought by Indian in 1927. Indian rolled the inline-4 into their own production bikes for a number of years before finally settling on the V-twin.

Almost 100 years after his death, Henderson’s passion for the inline-4 motorcycle engine has proven to be remarkably forward thinking. Many of the world’s fastest superbikes have used the configuration – albeit after rotating the engine 90 degrees into a transverse orientation rather than longitudinal.

The Ace Four you see here is due to be auctioned by Bonhams on the 19th of September with an estimated value of between £35,000 and £40,000 – making it a tidy investment for the right collector. I just hope they ride it occasionally.

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Founder & Senior Editor Silodrome

Ben Branch has had his work featured on CNN, Popular Mechanics, the official Smithsonian Magazine, Road & Track Magazine, the official Pinterest blog, the official eBay Motors blog, BuzzFeed, and many more.

Silodrome was founded by Ben back in 2010, in the years since the site has grown to become a world leader in the alternative and vintage motoring sector, with millions of readers around the world and hundreds of thousands of followers on social media.

Published by Ben Branch -