Lea & Francis started serious work on motorcycle development in 1911, and in 1912 a well designed machine, fitted with a V-twin 3¼ hp JAP engine, was launched. The motorcycle looked very smart, sporting full-length mudguards, long footboards and an enclosed chain drive. Other features included a quickly detachable rear wheel that did not require the chain to be disturbed during tyre changes and a very neat two-speed gearbox. The motorcycles had good roadholding and brakes and were well received by the public.
A notable early customer for the Lea-Francis motorcycle was George Bernard Shaw who had taken up motorcycling in his mid-fifties.
In 1913, a 3½hp was introduced. Lea-Francis entered their motorcycles in reliability trials as a means of gaining publicity, at which they faired reasonably well. In 1914, the gearbox was redesigned as a three-speed unit and a new motorcycle, utilising a V-twin MAG engine, was designed for use with a sidecar. Production was greatly scaled down during the early part of World War 1 and was suspended completely in 1916.
In 1919, a Lea-Francis motorcycle rushed the first pictures of the Armistice from London to Glasgow for publication in the Glasgow editions of the Daily Record and the Daily Mail. Production recommenced that year with the 3½-hp JAP engined model and later with an MAG engine as an option. In 1920, a larger motorcycle was designed for use with a sidecar using a 5hp MAG engine.
When production of Lea-Francis motorcycles finished in 1924 approximately 1500 machines had been produced of which about 20 are believed to have survived.