1961 Triumph Twenty-One 3TA
"Bathtub"

1961 TRIUMPH 3TA 'TWENTY-ONE' HAS BATHTUB STYLING.
The British home market had been hungry for cheap transportation after WWII, and commuter motorcycles helped fill that role. But England being...well, England, was wet and rainy and to prevent rust an owner needed to wipe his bike down each night after getting home from work. This was a chore that most came to hate. The British motorcycle industry responded with what are now called "enclosed bikes" as a way to make them easier to clean. Unfortunately, the gunk still found it's way into the new enclosures and rusted them from the inside out. Triumph had its swing at this fad, and it started with the 1959 Triumph 3TA Twenty One (called that because 350cc = 21 cubic inches) and its big-sister-bike, the 1959 5T Speed Twin (500). Both had bulbous sheetmetal enclosures over the entire rear section of the bike, along with a huge full-valance front mudguard (fender) and old fashioned headlight nacelle. The look quickly spawned the nickname "Bathtub Triumph" and the name stuck. 55-odd years later, that's still what we call them today.
1961 TRIUMPH TWENTY-ONE HAS UNIT CONSTRUCTION
Unit construction was all the rage in England back in the 1950s. Essentially, non-unit construction is when the engine, primary case and gearbox are all separate components that are bolted together in the frame. It was the old way of doing things, but it was time to move on. Unit construction meant taking all these separate component and "unitizing" them, that is placing them all in one common casing. Hence the term "unit construction". The first bike to benefit from this was the 350cc Twenty One, which converted over in 1957. Next up was the 500 twin (5T , TR5 and T100) in 1959. Their big 650 twin, once sharing components with the smaller non-unit 500 twins, was now a stand-alone engine design. It took until the 1963 model year to redesign the 650 twin into unit-construction. Some say that the 'unit-construction-revolution' happened because electrical-supplier Lucas (Prince of Darkness) announced that it would cease producing magnetos in 1963. This caused a complete re-engineering of virtually every British bike on the market at the time, and the decision was made at both Triumph and their parent company BSA to take this opportunity to go ahead and unitize their engines and gearboxes. It was a great move for Triumph, but BSA had mixed results at best, at least in terms of sales.

1961 Triumph Twenty-One SPECIFICATIONS

Model designation
Engine configuration
Displacement
Bore & Stroke
Compression Ratio
Fuel system
Primary drive
Clutch
Gearbox
Shifter
Final drive
Horsepower @ RPM
Frame
Rear Suspension
Front Suspension
Brakes, front
Brakes, rear
Tire, front
Tire, rear
Wheelbase
Overall length
Seat height
Curb weight
Fuel capacity
3TA
OHV air-cooled vertical twin
348cc / 21 ci
58.3mm x 65.5mm
7.5:1
1- Amal Monobloc
Chain
Multi-plate, wet
4-speed constant mesh
Right-foot
Chain
18.5hp @ 6500 rpm
Single down tube
Swing arm w/2 Shocks
Telescopic forks
7-inch SLS drum
7-inch SLS drum
3.25 X 17
3.25 X 17
53.5in / 1360mm
87in / 2115mm
28.5in / 724mm
340 lb / 154.4 kg
4.4 US gal / 16 L

Check out these TRIUMPH BOOKS

COMPLETE BOOK OF CLASSIC & MODERN TRIUMPHS


TRIUMPH MOTORCYCLES IN AMERICA


TRIUMPH MOTORCYCLE RESTORATION


TRIUMPH MOTORCYCLE RESTORATION, PRE-UNIT


TRIUMPH BONNEVILLE & TR6 RESTORATION GUIDE: 1956-1983


TALES OF TRIUMPH MOTORCYCLES & THE MERIDEN FACTORY


TRIUMPH 650 & 750 TWINS OWNERS WORKSHOP MANUAL, 1963-1983


TRIUMPH BONNEVILLE: ESSENTIAL BUYER’S GUIDE


TRIUMPH BONNEVILLE: PORTRAIT OF A LEGEND


ILLUSTRATED TRIUMPH BUYER’S GUIDE, by Roy Bacon


TRIUMPH BONNEVILLE, 2001-2015


TRIUMPH: PRODUCTION TESTERS TALES FROM MERIDEN


TRIUMPH MOTORCYCLE RESTORATION GUIDE


TRIUMPH OWNERS HANDBOOK, UNIT-CONSTRUCTION 350 & 500, Kindle


TRIUMPH ILLUSTRATED WORKSHOP MANUAL 1945-1955, by Clymer


TRIUMPH TWINS & TRIPLES


FACTORY-ORIGINAL TRIUMPH TWINS, 1938-1962


TRIUMPH BONNEVILLE & TR6, by Timothy Remus


TRIUMPH MOTORCYCLES: FROM SPEED TWIN TO BONNEVILLE


TRIUMPH MOTORCYCLES: THEIR RENAISSANCE & THE HINKLEY FACTORY


TRIUMPH PRE-UNIT TWINS OWNERS WORKSHOP MANUAL


TRIUMPH THRUXTON BONNEVILLE 1959-1969


TRIUMPH MOTORCYCLES ILLUSTRATED WORKSHOP MANUAL 1937-1951, by Clymer


TURNER’S TRIUMPHS: EDWARD TURNER & HIS TRIUMPHS


TRIUMPH TWIN RESTORATION, by Roy Bacon


TRIUMPH TIGER CUB & TERRIER 1952-1968, Haynes Repair Manual


TRIUMPH 675 DAYTONA & SPEED TRIPLE REPAIR MANUAL 2006-2010, Haynes


CLASSIC MOTORCYCLES: TRIUMPH


TRIUMPH BONNEVILLE YEAR BY YEAR


TRIUMPH TRIPLES


TRIUMPH RACING MOTORCYCLES IN AMERICA


TRIUMPH MOTORCYCLES


TRIUMPH, by Roy Bacon


TRIUMPH 750/900 TRIPLES & 1200 FOURS 1991-1999, Haynes Repair Manual


TRIUMPH TROPHY BIBLE


TRIUMPH DAYTONA, SPEED TRIPLE SPRINT & TIGER: 885/955 1997-2005, Haynes Repair Manual


BSA & TRIUMPH TRIPLES GOLD PORTFOLIO 1968-1976


TRIUMPH TRIDENT OWNERS WORKSHOP MANUAL, by Haynes


TRIUMPH: A CENTURY OF PASSION & POWER


TRIUMPH BONNEVILLE, by Osprey


TRIUMPH TIGER 100 & 110, 1939-1961, by Roy Bacon


TRIUMPH TIGER 100 & DAYTONA


TRIUMPH BONNEVILLE, by Crowood


TRIUMPH by Don Morley


TRIUMPH TRIPLES & FOURS 1991 & 2004


TRIUMPH 350 & 500 1957-1974 ESSENTIAL BUYERS GUIDE


BONNIE: THE DEVELOPMENT OF THE TRIUMPH BONNEVILLE


TRIUMPH SINGLES: EARLY DAYS TO 1974, by Roy Bacon


TRIUMPH: RETURN OF THE LEGEND


TRIUMPH FUEL INJECTED TRIPLES 1997-2000


BOOK OF TRIUMPH TWINS 1968-1969, by Floyd Clymer


THE TRIUMPH STORY: RACING & PRODUCTION MODELS 1902-PRESENT


TRIUMPH 350 & 500 TWINS 1958-1973, Haynes Repair Manual


TRIUMPH BONNEVILLE 2001-=2008 ROAD TEST PORTFOLIO


HINKLEY TRIPLES & FOURS


TRIUMPH PRE-UNIT TWINS


HINKLEY TRIUMPHS: THE FIRST GENERATION


TRIUMPH BONNEVILLE BIBLE: ALL MODELS 1959-1983


TRIUMPH TWENTY-ONE TO DAYTONA: C CLASS 350 & 500 TWINS


ORIGINAL TRIUMPH BONNEVILLE


TRIUMPH 650 & 750 TWINS


TRIUMPH MOTORCYCLES & CUSTOM BIKES


TRIUMPH MOTORCYCLES


TRIUMPH, THE LEGENDS SERIES


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TRIUMPH SPEED TWIN & THUNDERBIRD BIBLE


TRIUMPH BONNEVILLE T120/T140


TRIUMPH MOTORCYCLES FROM 1950-1983


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TRIUMPH THUNDERBIRD, TROPHY & TIGER ESSENTIAL BUYERS GUIDE


TRIUMPH TIGER CUB BIBLE


ROAD RACING HISTORY OF THE TRIUMPH 500 UNIT TWIN


EDWARD TURNER: THE MAN BEHIND THE MOTORCYCLES


SAVE THE BONNEVILLE: THE INSIDE STORY OF THE MERIDEN WORKERS CO-OP


TRIUMPH DAYTONA 1991-2006 ROAD TEST PORTFOLIO


TRIUMPH DAYTONA 2003-2009 ROAD TEST PORTFOLIO


TRIUMPH TIGER 100 / DAYTONA: DEVELOPMENT HISTORY


TRIUMPH, by Daniel Gilpin


BOOK OF TRIUMPH MOTORCYCLES ILLUSTRATED SHOP MANUAL 1935-1939


TRIUMPH: THE RACING STORY


TRIUMPH BONNEVILLE T120 1959-1974, by Roy Bacon


TRIUMPH BONNEVILLE GOLD PORTFOLIO 1959-1983


TRIUMPH TRIDENT SUPER PROFILE


ILLUSTRATED TRIUMPH BUYERS GUIDE, by Roy Bacon






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