The most likely motorcycle featured on Happy Days would arguably be the Triumph, as it seems to stick in every ones memory. View the attached video closely, listen to the classical music of it's pipes, that certain growl, and make up your own mind. The Fonz’s clothing started a fashion industry craze in the late 70’s with a plain white t shirt under a leather jacket styled in that WW2 Bomber look. The Fonz made everything cool and sexy. The girls loved the look!.... I digress.
The motorcycles mainly featured were Triumphs and were most likely the 449cc TR5 Trophy Twin first introduced at the 1948 Motor Cycle Show.
For road use, it was a low compression version of the Grand. Prix. engine. This model was entered by Allen Jefferies, in the 1948 International Six Days Trial and the Triumph cleaned up this event.
The Knucklehead Harley Davidson that was also a contestant, t'was given it’s name by Harley because of the exclusive shape of the rocker covers, like a shiny set of knuckles on a clenched fist. This had a twin pushrod motor that replaced the previous Flathead (no not a fish) and in turn replaced by the Panhead engined model in 1948. The Fonz was also pictured along side a Harley Davidson
Sportster. Most likely all but the Triumph, were purely promotional events to seize the moment of the day.
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TRY THIS ONE ON FOR SIZE