One of the more interesting motorcycles to come from England was the Ariel Square Four. I had the opportunity to see one of these motorcycles at the Spring 2012 Show of the British Iron Association of Massachusetts.
A 1955 Ariel Square Four Mark II
The story of this motorcycle begins in the 1920s when Edward Turner, a London motorcycle dealer, thought of a way to build a compact four-cylinder engine, by mounting the engine cylinders in a two-by-two pattern. This design solved two problems – it dealt with the overheating problems that were particular to inline four-cylinder engines that were mounted parallel to the motorcycle’s centerline and eliminated the width problems if the four-cylinder engine was mounted perpendicular to the motorcycle’s centerline. By the way, as many of you know, Edward Turner went on to become a major designer of Triumph motorcycles. However in the 1920s, Turner had to look hard to find a motorcycle manufacturer to take a chance on this engine design. Eventually, Edward Turner convinced the Ariel people to proceed with the detailed design of this engine. The initial result was a 500cc four-cylinder engine. Later this engine design was increased to 600cc. In 1936, the engine size was raised to 1,000cc with the release of the Ariel Model 4G 997cc engine. This engine continued until 1953 when the four pipe Mark II engine was released. The motorcycle pictured in this post is the later Mark II engine. The earlier Ariel Square Four models had only two pipes coming from the engine which made it look somewhat like an oversize twin cylinder design.
Notice How the Cylinder Exhaust Pipes Tastefully Emerge From The Ariel Square Four Mark II Engine
The following road test was included in the The Motor Cycle in 1952. As can be seen from the test, the Ariel Square Four Mark II was a good performer for its day.
1952 Ariel Square Four Road Test From “The Motor Cycle”
The reported top speed in above road test was 97 miles per hour, just slightly below the 100 miles per hour benchmark.
The Ariel Square Four Has An Elegant Design
The rear suspension uses a plunger type design, which apparently needed frequent lubrication.
The Engine and the Transmission Were Separate Units
The Ariel Square Four had a four-speed transmission which the Ariel thought was well matched to the engine. Ariel bragged how the engine could be driven from 10 to 100 miles per hour in the top gear. This claim is not substantiated by The Motor Cycle road test where the Minimum Non-Snatch Speed measured was 13 miles per hour in top gear. Also as noted earlier, during the road test a maximum speed of 100 miles per hour could not be reached.
The Handlebars Lack the “Clutter” of Modern Motorcycles
The Ariel Square Four was made until 1959 when Ariel Motors, Limited concentrated on medium displacement two-stroke machines that were a blend of motorcycle and scooter designs. The Ariel Square Four motorcycles are interesting motorcycles and represents some of the better motorcycle engineering that came from England.