Ariel Square Four

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Motorworld’s newspaper № 18
Test-drive video
The idea for creating the Ariel Square Four motorcycle came to Edward Turner in 1928. While looking for work at the time, he was showing around his drawings of an engine design to motorcycle manufacturers. His engine was very special due to its unusual configuration: four cylinders were placed at the corners of a square. Two bent shafts were linked by a gear drive (its crowns were cut straight in the centrally located flywheels); connecting rods were fixed unto flywheels via consoles, except for the left rear cylinder, from which the gear was connecting to the transmission. All valves were driven by a central, chain-driven overhead camshaft. Although the BSA company rejected the idea of making such an engine, this design was approved by Ariel.

Internal Engine Arrangement of Ariel Square Four

Ariel Square Four is one of the most charismatic British motorcycles created after the global economic crisis of the 1930s. The combination of its 4-cylinder engine with its 996-cc capacity resulted in a unique motorcycle that was in a class of its own because such a combination is rarely used with classic motorcycles. Despite its big mass of 197 kg, this motorcycle would easily achieve the speed of 160 km/h, and it was easy to drive.

Ariel Square Four, nicknamed «Squariel», was well accepted by clients, even despite its frequent problems with engine overheating due to poor cooling of its two “rear” cylinders. During the production period, starting with a prototype in 1930 and until this model was discontinued in 1958, a total of 15,641 motorcycles were manufactured.

The sidecar is a 1948 Bernardet Grand Routier GR.48, on an original 1948 T frame.
It was also produced in the model Grand Sport GS.48 Records du Monde type Avion
It was the last sidecar ever produced between 1947 to 1949 by Bernardet before the company switched to scooters, and they are still the most famous of the whole production! © Archives Bernardet Family

Manufacturer Ariel, Great Britain
Years of manufacture 1931 – 1958
Quantity produced, units 15 641
Price 95 £
Today’s value 6 187 $
Type 4-cylinder, OHV, air-cooled
Engine capacity, cc 996
Bore and stroke, mm 65 х 75
Engine rating 38 h.p. at 5400 rpm
Sparking Magneto Lucas
Carburetor Solex
Battery 6 V
Clutch Single dry plate
Transmission 4-speed
Frame type Tubular
Front suspension With a frictional damper
Rear suspension Rigid (after 1946: telescopic)
Brakes Drum type, on all wheels
Wheel size Front: 3.25 х 19, rear: 4.00 х 18
Length, mm
2 083
Width, mm
Height, mm
1 030*
Wheelbase, mm
1 422
Ground clearance, mm
Seat height
Mass, kg
Gas tank size, l
Maximum speed, km/h
Range, km
* – Data on the results of the measurement of the “Motorworld by V.Sheyanov” exhibit.



The Modern Ariel Motor Cycle. 1939-48 Owner’s Guide. The Square Four