Triumph Bonneville

1959 Triumph Bonneville emblem

Triumph Bonneville Background & History

The Triumph Bonneville represented the top of the food chain when it came to Triumph 650 twins when introduced in 1959. It was the final step in the evolution of Triumph’s big vertical twin, with each step faster and more powerful than the last.

1965 Triumph Bonneville

This 1965 Triumph Bonneville represents both Triumph and the Bonneville at their peak.

During the 1920s and 30s, motorcycles developed and improved dramatically. One basic engine layout ruled the era: single-cylinder machines. They started out as side-valve (flathead) designs, but soon graduated on to overhead valves (OHV) as performance steadily improved. By the mid-1930s, displacement and power output had nearly reached their practical limits at around 500cc and 25 horsepower. Adding more displacement, or extracting more power by revving the engines faster only led to horrible engine vibrations that were hard on engines and riders alike. Many solutions were attempted but nothing seemed to work.

Shortly after Jack Sangster bought Ariel Motorcycles he brought over a promising new designer named Edward Turner, who promptly designed the first Ariel Square Four. When Ariel bought Triumph, Turner was put onto the task of solving the vibration problems the company, and the entire industry, was experiencing.

1938 Triumph 5T Speed Twin-R

The 500cc 1938 Triumph 5T Speed Twin changed the world and the rest of the industry rushed to follow.  But they never caught up to Triumph.

New Vertical Twin

Turner’s solution took a whole new approach. He split that 500cc of displacement into two parallel cylinders rising and falling together on a 360-degree crankshaft, but firing alternately. The new ‘vertical twin’ as it was dubbed was lighter, made more power, loved to rev, and didn’t have nearly the vibration penalty of the big singles. In 1937, Triumph launched the new engine in a new bike, the 500cc 1938 Triumph 5T Speed Twin. It was an instant hit and changed the entire motorcycle landscape. Suddenly, all the big singles had been outclassed. Most of the British motorcycle industry rushed to bring their own vertical twins to market.

1951 Triumph T100 Tiger

This 500cc 1951 Triumph T100 Tiger offered hotter cams, higher compression and a bigger carb than the Speed Twin.  Triumph gave the same 'Tiger treatment' to their 650 creating the T110 Tiger.

Triumph Leads the Industry

During this era, and beginning with the Speed Twin, Triumph ruled the roost, always setting the pace of innovation, always leading the way with newer, bigger, faster bikes. As quickly as the rest would catch up, Triumph would launch another bike that left them all in the dust. The Speed Twin did it first in 1938. Then, higher compression, hotter cams and a bigger carburetor were added, boosting horsepower, creating the ‘hot rod-version’, with the 1939 Triumph T100 Tiger. World War 2 broke out in 1939 and all civilian production ended until 1946, but when it did, Triumph was back with a vengeance.

Several other British companies began fielding their own 500cc vertical twins, including BSA, Norton, Royal Enfield and Matchless/AJS. But no sooner than they started to catch up Triumph raised the bar by boring and stroking the 500 out to 649cc thereby creating the 1950 Triumph 6T Thunderbird. And the race was on, the race to build the biggest, baddest bike. Several boosted displacement, Royal Enfield and Norton even passing Triumph’s 650cc displacement. Triumph responded by applying the ‘Tiger-treatment’ to their new 650 and the 1954 Triumph T110 Tiger became just about the fastest bike on the market. Faster than most fast cars, too. Again, the market rushed to catch up. Just when some of them started to gain a little ground Triumph did it again. They developed a new alloy cylinder head dubbed the “Delta Head”. It was not only lighter and offered better cooling but it flowed better and so made even more power. They introduced it in a whole new bike, the 1956 Triumph TR6. Once again, Triumph reigned in performance. But, in the motorcycle business, “too much is never enough”.

1956 Triumph TR6B-R

The 650cc 1956 Triumph TR6 upped the ante again with still more power, thanks to the new alloy Delta Head.

During this era, and beginning with the Speed Twin, Triumph ruled the roost, always setting the pace of innovation, always leading the way with newer, bigger, faster bikes. As quickly as the rest would catch up, Triumph would launch another bike that left them all in the dust. The Speed Twin did it first in 1938. Then, higher compression, hotter cams and a bigger carburetor were added, boosting horsepower, creating the ‘hot rod-version’, with the 1939 Triumph T100 Tiger. World War 2 broke out in 1939 and all civilian production ended until 1946, but when it did, Triumph was back with a vengeance.

Several other British companies began fielding their own 500cc vertical twins, including BSA, Norton, Royal Enfield and Matchless/AJS. But no sooner than they started to catch up Triumph raised the bar by boring and stroking the 500 out to 649cc thereby creating the 1950 Triumph 6T Thunderbird. And the race was on, the race to build the biggest, baddest bike. Several boosted displacement, Royal Enfield and Norton even passing Triumph’s 650cc displacement. Triumph responded by applying the ‘Tiger-treatment’ to their new 650 and the 1954 Triumph T110 Tiger became just about the fastest bike on the market. Faster than most fast cars, too. Again, the market rushed to catch up. Just when some of them started to gain a little ground Triumph did it again. They developed a new alloy cylinder head dubbed the “Delta Head”. It was not only lighter and offered better cooling but it flowed better and so made even more power. They introduced it in a whole new bike, the 1956 Triumph TR6. Once again, Triumph reigned in performance. But, in the motorcycle business, “too much is never enough”.

1959 Triumph Bonneville

When the 1959 Triumph Bonneville came out it was draped in the stodgy bodywork from the Thunderbird/Tiger line.  By 1960, they'd changed that to the nicer looking TR6 bodywork.

Triumph Bonneville is Born

When the Triumph Bonneville was first introduced in 1959, it was based on the hottest bike they made at that time, the T110 Tiger, which was itself based on the 6T Thunderbird line. The T-Bird was the entry-level Triumph 650 and meant to satisfy the practical rider/commuter with things like fully valanced mudguards, a large fuel tank and a headlight nacelle. So, when the Bonneville launched in 1959 it was clad with the same bodywork as the T110 Tiger and 6T Thunderbird. This and the odd two-tone color scheme of orange and creme combined to make the bike look stodgy and understated. Considering it was meant to be the hottest motorcycle on the planet, the styling missed the mark.

1962 Triumph Bonneville

This 1962 Triumph Bonneville shows the results of the 1960 restyling.  It now shared bodywork with the TR6.

Triumph Bonneville gets a New Suit

When the Triumph Bonneville was first introduced in 1959, it was based on the hottest bike they made at that time, the T110 Tiger, which was itself based on the 6T Thunderbird line. The T-Bird was the entry-level Triumph 650 and meant to satisfy the practical rider/commuter with things like fully valanced mudguards, a large fuel tank and a headlight nacelle. So, when the Bonneville launched in 1959 it was clad with the same bodywork as the T110 Tiger and 6T Thunderbird. This and the odd two-tone color scheme of orange and creme combined to make the bike look stodgy and understated. Considering it was meant to be the hottest motorcycle on the planet, the styling missed the mark.

Triumph Unit vs Non-Unit engines

LEFT: 1962-and-earlier Triumph 650 twins were made with non-unit (or pre-unit) construction. The engine, gearbox and primary chain case were separate components bolted together with a system of brackets.  RIGHT: 1963-and-newer 650s got unit-construction with all three components housed in a single unitized casing.

Triumph Bonneville goes Unit-Construction

In 1963, Triumph and BSA converted their big twins (650s) from non-unit construction to unit-construction. Non-unit means that the engine, the gearbox and the primary chain case were three separate components held together by a system of brackets. Unit construction means that all of these components are housed in a single unitized casing, hence the name. Unit construction engines are generally smaller, lighter, stronger, easier and cheaper to produce, easier to work on and maintain.

1970 Triumph Bonneville

The 1970 Triumph Bonneville was the last year prior to the Oil-in-Frame bikes.

Storm Clouds from the East

These unit-construction Triumph Bonnevilles stormed through the 1960s breaking sales records each year, until the Japanese arrived with their big guns in 1968, then it was pretty much game over for the Brits. They had enjoyed a market with virtually no competition, and now the Japanese began fielding bigger and better machines like the Honda DOHC 450 (originally known as the “Black Bomber”), the Honda CB750 and the wild Kawasaki Mach 3 500cc 2-stroke triple.

By this time, Triumph had gotten all the power out of their ancient (designed in 1937) 650 twin that they were going to get without suffering reliability issues far worse than the ones they were already dealing with (oil leaks, sketchy electrics, etc.). The answer would have been a complete redesign of all of Triumph’s engines, modernizing them to be more like the Japanese bikes. But, that never happened. The beleaguered Brits simply didn’t have the money to pull it off.

1971 Triumph Bonneville

While the 1971 Triumph Bonneville was a handsome machine, many traditionalists hated the new looks.  I was working in a Triumph-BSA-Norton dealership when the first ones arrived.  I thought they were gorgeous, and we all hoped they would sell well against Japanese bikes.  Unfortunately, that never happened.

Oil-n-Frame Triumph Bonneville

These unit-construction Triumph Bonnevilles stormed through the 1960s breaking sales records each year, until the Japanese arrived with their big guns in 1968, then it was pretty much game over for the Brits. They had enjoyed a market with virtually no competition, and now the Japanese began fielding bigger and better machines like the Honda DOHC 450 (originally known as the “Black Bomber”), the Honda CB750 and the wild Kawasaki Mach 3 500cc 2-stroke triple.

By this time, Triumph had gotten all the power out of their ancient (designed in 1937) 650 twin that they were going to get without suffering reliability issues far worse than the ones they were already dealing with (oil leaks, sketchy electrics, etc.). The answer would have been a complete redesign of all of Triumph’s engines, modernizing them to be more like the Japanese bikes. But, that never happened. The beleaguered Brits simply didn’t have the money to pull it off.

1977 Triumph Bonneville Silver Jubilee

Triumph built the 1977 Triumph Bonneville Silver Jubilee as a limited edition special to celebrate the 25th anniversary of Queen Elizabeth's coronation.

Big Trouble at Home

In 1972, parent company BSA attempted a merger with Norton-Villiers, the only other British motorcycle manufacturer still standing. It didn’t help, and BSA failed anyway. That left Triumph in the hands of Norton who announced in 1974 their plans to close the Meriden factory and move all Triumph production over to Norton’s factory in Donington Park. The Triumph workers revolted, and occupied the Meriden plant for most of the 1974 model year, not allowing anything to enter or leave the factory. As a result, there are very few 1974 Triumph Bonnevilles in existence. Norton finally relented and in 1975 the workers formed a co-op (the Meriden Co-op) to continue Triumph production. Unfortunately, it was doomed from the start as the new co-op was underfunded and got no help from the socialist government in power at the time in England.

1983 Triumph TSS

The 1983 Triumph Bonneville TSS was the ultimate and final evolution of the vertical twin launched in 1938.  An 8-valve Westlake head and a forged steel crank were just a few of the tricks used to make 58 hp, relatively vibration-free.  Alas it was too little too late.

Triumph Bonneville: Life After Death

While they produced some nice bikes and some very special models during this time, each year production numbers went down and by around 1982 they couldn’t pay their bills anymore and many of their suppliers stopped sending the parts needed to assemble the bikes. In 1983, they called it quits and the whole brand was purchased by billionaire developer John Bloor who had plans to modernize the entire Triumph line. This would take years of course, and in the meantime, Les Harris was granted the rights to continue classic Bonneville construction in the interim. This allowed Triumph to make the claim to fame of being the longest continuously produced motorcycle brand in the world, continuing uninterrupted from 1902 to the present. Even Harley-Davidson can’t say that, they started in 1903. Harris, who owned Racing Spares Company out of Devon, England hand built Harris-Bonnevilles until 1988 when he finally ran out of Triumph parts, just in time for the new era of Triumphs to begin production in the new Triumph’s brand new factory in Hinkley, England. A new and growing line of thoroughly modern 3- and 4-cylinder bikes re-introduced the world to the Triumph brand. It took until 2008 for the first modern Triumph Bonneville to arrive. Again, throughly modern, they featured DOHC, 4 valves-per-cylinder, a 270-degree crankshaft and 800cc of displacement. Like all modern Triumphs, they’re great bike, fast, reliable and handsome.

Les Harris Bonneville

The Harris-Bonneville was hand built in low numbers by Les Harris between the closing of the Meriden factory in 1983 and the opening of the new Hinkley factory in 1989.

Triumph Model Name Nomenclature

Triumph used several different naming conventions for its many models of motorcycles. Almost all their bikes had names, but most also had alphanumeric designations. The following are share one thing in common, the numbers-part is supposed to represent the top speed of the bike. Here's a list by displacement, and hence top speed:

T70 Tiger 70 - 250cc single (70mph? Maybe 65 with a tail wind)

T80 Tiger 80- 350 single (80mph? 75mph was possible)

T90 Tiger 90 - 500 single (90mph? Again, close, but no cigar)

T100 Tiger - 500 twin (100mph? Again, close, very close)

T110 Tiger - 650 twin (110mph? On a very good day, yes.)

T120 Bonneville - 650 twin (120mph? Not quite)

T140 Bonneville - 750 twin (140mph? No way, not even close)

T150 Trident - 750 triple (150mph? No, 120mph tops)

T160 Trident - 750 triple (150mph? 120)

Most Triumph owners preferred to call their Triumph's by their sexy model names like Bonneville, Tiger and Trident. Few used the alphanumeric labels.

Triumph Bonneville by the Year

1959 T120 Bonneville
1960 T120 Bonneville
1961 T120 Bonneville
1962 T120 Bonneville
1963 T120 Bonneville
1964 T120 Bonneville
1965 T120 Bonneville
1966 T120 Bonneville
1967 T120 Bonneville
1968 T120 Bonneville
1969 T120 Bonneville
1970 T120 Bonneville
1971 T120 Bonneville
1972 T120 Bonneville
1973 T140V Bonneville
1974 T140V Bonneville
1975 T140V Bonneville
1976 T140E Bonneville
1977 T140E Bonneville
1977 T140J Silver Jubilee
1978 T140E Bonneville
1979 T140E Bonneville
1979 T140E Bonneville
1979 T140D Bonneville Special
1980 T140E Bonneville
1981 T140E & ES Bonneville
1982 T140E & ES Bonneville
1983 T140E & ES Bonneville

Triumph Bonneville Books

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