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Thread: Lennon Rogers Posts Isle of Man TT winners since 1907

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    Senior Member Ted Dillard's Avatar
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    Lennon Rogers Posts Isle of Man TT winners since 1907

    Lennon sent me an email today - seems he's been working on a plot of the speeds of the IOM races, including electric - also including this year's average lap speed of 121.824 by Mugen, the first year they broke 120mph.

    Here's his email:


    Here's a plot I put together of the fastest average speed for the Isle of Man TT winners since 1907 (gas & electric). As of 2018, electrics are at the same average speed as the gas bikes in ~2000 (though electric is only one lap versus the gas doing multiple).


    The most similar rate of increase in gas bikes occurred after WWI. Factors that may have contributed to these increases are pasted below (from various TT history books / resources).

    Note the races were canceled in:
    1915-1919 (WWI)
    1940-1946 (WWII)
    2001 (Foot and Mouth)

    • 1925 "Major improvements to the roads of the TT course in the mid-1920s saw increased use of tarred surfaces, particularly over the mountain section. This made a significant contribution to the setting of new race and lap records in all the classes in 1925
    • 1926 This year they banned alcohol-based fuels. These had helped increase speeds in previous years. After this year competitors were restricted to using commercially available petrol-benzole mixtures
    • 1927 By the mid-1920s upgrades included: replacing the single-speeds and belt drives to three and four-speed gearboxes with chain drives. Rim brakes with tank mounted levers replaced by drum brakes cable driven by a hand and foot pedal. After the last victory of a side-valve engine in 1922, overhead valves became commonplace in 1926 when Alec Bennett won the junior on one. Advances in metallurgy allowed greater use of aluminum components like cylinder heads. Component suppliers improved essential items like spark plugs, carbs, magnetos. Advances made by petrol and oil companies allowed race machines to run on compression ratios of about 6.5:1.

    Last edited by Ted Dillard; 10 June 2018 at 1131.
    Power in Flux: The History of Electric Motorcycles

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