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The Triumph Twenty One (also known as the 3TA) is a standard
There are two explanations for the 'Twenty One' name spelt out in full on the side panels. The first explanation is that it celebrates the twenty-first anniversary of 
In 1959 the Twenty One was rebranded the Triumph 3TA and also produced as a 500 cc version, the Triumph 5TA, which was also referred to as the 'new Speed Twin'. The 'A' designation was a reference to the fact that both motorcycles were fitted with an alternator as standard, as the pre-unit models had been fitted with a Dynamo. The original versions of both the 350 cc and 500 cc models had the fully enclosed rear end which was fashionable in the late 1950s. It was not popular with American customers, where the extra weather protection was less important however, and it got called the '
The 3TA and the 5TA both continued in production until 1966 when they were survived by their sportier versions, the T90 and T100 respectively.
motorcycle
A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruisin ...
made by Triumph Engineering Co Ltd
Triumph Engineering Co Ltd was a British motorcycle manufacturing company, based originally in Coventry and then in Meriden. A new company, Triumph Motorcycles Ltd, based in Hinckley, gained the name rights after the end of the company in the ...
in Coventry
Coventry ( or ) is a city in the West Midlands, England. It is on the River Sherbourne. Coventry has been a large settlement for centuries, although it was not founded and given its city status until the Middle Ages. The city is governed ...
. The ''Model Twenty One'' was the first of the Triumph unit construction : ''For the vehicle design where the vehicle's skin is used as a load-bearing element, see Monocoque.''
Unit construction is the design of larger motorcycles where the engine and gearbox components share a single casing. This sometimes includes ...
twin cylinder motorcycles. Rebranded as the Triumph 3TA in 1959 it continued in production until 1966 when it was survived by the Triumph T90, its sports version.
Development
Launched in 1957 the ''Model Twenty One'' was the first of the Triumphunit construction : ''For the vehicle design where the vehicle's skin is used as a load-bearing element, see Monocoque.''
Unit construction is the design of larger motorcycles where the engine and gearbox components share a single casing. This sometimes includes ...
twin cylinder motorcycles from the Meriden factory. With a capacity of 349 cc, the engine was a classic Edward Turner design with a 360 degree crankshaft, twin gear driven camshafts and twin plunger oil pump. The cylinder block was cast iron with an alloy head and separate rocker boxes. The engine was dry sump lubrication and there was a single Amal Monobloc carburettor. Drive was by a conventional four speed gearbox, with a right foot gear lever.
There are two explanations for the 'Twenty One' name spelt out in full on the side panels. The first explanation is that it celebrates the twenty-first anniversary of Triumph Engineering Co Ltd
Triumph Engineering Co Ltd was a British motorcycle manufacturing company, based originally in Coventry and then in Meriden. A new company, Triumph Motorcycles Ltd, based in Hinckley, gained the name rights after the end of the company in the ...
. The second explanation is that the important US export market rated motorcycle engine displacement
Engine displacement is the measure of the cylinder volume swept by all of the pistons of a piston engine, excluding the combustion chambers. It is commonly used as an expression of an engine's size, and by extension as a loose indicator of t ...
in cubic inches and 21 cubic inches equates to 350 cc.
In 1959 the Twenty One was rebranded the Triumph 3TA and also produced as a 500 cc version, the Triumph 5TA, which was also referred to as the 'new Speed Twin'. The 'A' designation was a reference to the fact that both motorcycles were fitted with an alternator as standard, as the pre-unit models had been fitted with a Dynamo. The original versions of both the 350 cc and 500 cc models had the fully enclosed rear end which was fashionable in the late 1950s. It was not popular with American customers, where the extra weather protection was less important however, and it got called the 'bathtub
A bathtub, also known simply as a bath or tub, is a container for holding water in which a person or animal may bathe. Most modern bathtubs are made of thermoformed acrylic, porcelain-enameled steel or cast iron, or fiberglass-reinforced p ...
'. They also found that the extra sheet metal made access for servicing more complicated. Only the final 3TA model for 1966 dispensed entirely with the rear fairing.
The 3TA and the 5TA both continued in production until 1966 when they were survived by their sportier versions, the T90 and T100 respectively.
See also
*List of Triumph motorcycles
Motorcycles produced under the Triumph brand, by both the original company, Triumph Engineering Co Ltd, and its later incarnations, and the current Triumph Motorcycles Ltd.
Triumph Engineering Co Ltd
Known as the Meriden, West Midlands, UK era ...
References
{{Triumph motorcycles Meriden Twenty One Motorcycles powered by straight-twin engines