IT'S BEEN SAID MANY TIMES, and with justification, that the public doesn’t know what it wants until it sees it. So it was with the seminal 498cc Triumph Speed Twin, launched at the London Motorcycle Show at Olympia in November 1937.

Until that momentous day, Britain had been predominantly a nation of thumper riders, happy to chug about its largely poverty stricken business on a huge range of worthy, if not exactly scintillating single cylinder machines from BSA, Norton, Ariel, AJS, Matchless, Royal Enfield and (indeed) Triumph—to name just the leaders in the field.

True, there were dozens of twin cylinder bikes on the market catering for the privileged few who could afford them—and even the odd four-cylinder piece of exotica for those who preferred to ride against the tide of convention and enjoyed flaunting their singular, if not outrightly Bohemian, tastes.

But in the main, if, during the mid-1930s, you rode a motorcycle (certainly a four-stroke motorcycle), the chances were that it had one cylinder and two side valves and three or four speeds on a hand-change lever—all of which was a perfectly agreeable enough formula and one that had mobilised the nation for the past three decades and was well suited to the winding, rural A and B roads criss-crossing Shakespeare’s sceptred isle.

A single cylinder machine, after all, had numerous advantages over a twin, not least that it was cheaper to manufacture, and therefore cheaper to buy. It also required a shorter (perceived) leap of technical nous and was deemed easier to repair. A single cylinder motorcycle was a lighter machine, and therefore offered—or, at least, implied—better handling. And perhaps most crucially, a single was a sober and conservative choice in a land where modernism was still largely treated with suspicion and deemed to be the province of Johnny Foreigner and his filthy Bavarian/Slavic/Latin/Gallic ways.

The bike that helped bring the post-Victorian, Empire building, white-is-right Brits up to swarthy continental speeds was the ’37 Triumph Speed Twin, one of the shrewdest, slickest, most accomplished commercial moves in the history of British biking.

Designed by Edward Turner, then managing director of Triumph Engineering Company Ltd, the Speed Twin gave the market exactly what it needed (but didn’t know it wanted) and at a time when it would most appreciate it.

This, after all, was the era of increasingly worrying Spanish, Italian and German fascism; an age when, having endured the war to end all wars and having struggled through years of depression, Britain was desperate for something—anything—to help lift the gloom and roll out a carpet to a better, cleaner, brighter and faster future.

Not that the Speed Twin alone was the panacea the country needed. But it was, however, a small and very distinct gem twinkling in a world of despair that would become hugely more despairing less than two years later.

But Turner’s Twin didn’t simply happen. Rather, it arrived as part of a revamp package of Triumph’s existing range of solid (and slightly dour) 250cc, 350cc and 500cc singles created by Val Page, arguably the greatest of all British motorcycle designers.

Page had also designed a solid (if slightly dour) parallel twin, the Model 6/1, introduced in 1933 for the ’34 season.

The 6/1 was a heavyweight, OHV, 70mm x 84mm, 649cc machine intended largely for sidecar work; an interesting and technically well-conceived, wet-sump design with a bolt-on gearbox, a single camshaft at the rear of the cylinder barrels (an arrangement later typified by BSA twins), a single carburettor, and a helically-geared primary drive with no intermediate gear—which meant that the engine ran backwards.

At £75 plus change, this bike was to be Triumph’s flagship and a full £20 more expensive than, for instance, the company’s mid-range OHV Silent Scout then selling at around £55.

But either the buying market wasn’t ready for the 6/1, or the economy was still too weak, or other aspects of the design simply weren’t sufficiently appealing (such as the old-fashioned hand change four-speed gearbox when positive stop foot-change was being offered by one or two rival marques; foot change was, note, an option in the last year of production).

Regardless, no more than around one hundred 6/1s were built (and substantially less than this according to some estimates), and Page’s masterpiece died a slow and ignominious death.

Things changed dramatically in 1936 when Edward Turner arrived at Triumph (having followed Val Page from Ariel) and was promptly charged with the responsibility for not only bringing Triumph up to date, but pushing it to the forefront of a largely stagnating industry.

Three immediate targets were Page’s single-cylinder and unimaginatively named Model 2/, Model 3/ and Model 5/ series that were available is various specifications for the road riding and sporting man.

The following year (1937), bikes from this range were parlayed by Turner into the more dashing sounding Tiger 70 (249cc), Tiger 80 (343cc) and Tiger 90 (493cc) OHV singles. And, to cap it all, a new flagship was introduced; the 498cc, OHV, 5T Speed Twin.

At first glance, the Speed Twin, with its 7:1 compression, 63mm x 80mm bore and stroke, and 28bhp was nothing other than a very attractive twin port single with visually little else to differentiate it from the three Tigers now prowling for business.

The Triumph trick was to serve up a twin cylinder dish in a way that made it irresistible even to singles men; a feat that was achieved by keeping the engine as small and as narrow and as “tight” as possible, whilst generally trimming the fat everywhere else. It was nothing less than a quiet and bloodless revolution that generated the much needed momentum to carry the company through the next two decades.

Where Val Page’s model 6/1 was a 650cc machine, Turner’s Speed Twin was 498cc. Where Val Page’s 6/1 had a 70mm bore, Turner’s Twin was 63mm, and those reduced dimensions no doubt helped keep the engine narrow, thereby making it acceptable as an “honorary” single.

To the inexperienced eye, however, there was little significant difference between the profiles of the Speed Twin and Val Page’s Model 6/1. Both were rigid framed, girder-forked, twin cylinder bikes with sprung saddles and a chrome-and-paint petrol tank. Yes, the Model 6/1 was a slightly bulkier machine. Nevertheless, the similarities were far greater than the differences.

But few discerning motorcyclists were blind to the styling subtleties that made the Speed Twin such a giant leap forward. It was in the graceful sweep of the fuel tank, the rakishness of the lines from the headstock to the rear hub, and in the overall poise that was later imitated by many other manufacturers, but never carried off quite so well.

Additionally, and crucially, the Speed Twin had exactly the right name and identity for a speed obsessed nation that, ironically, had barely a stretch of decent dual carriage to run a fast bike on let alone a motorway (the Preston by-pass, being the first built stretch of the M6, would take another twenty one years to arrive; while Germany had built its first autobahn five years earlier in 1932).

And what price this new found flash & dash? Just £75; exactly what it had cost to buy a 6/1 four years earlier (although the 6/1, which had been discontinued the year before the launch of the Speed Twin, had seen a price drop to £70).

In any case, the timing was just right, and the Speed 90mph Twin was an instant hit. And so it ought to have been, because Turner had actually been this way before during his stint at Ariel in the early 1930s when he revamped Val Page’s successful Red Hunter series of machines. With the Speed Twin, Turner simply refined a formula that needed only an extra cylinder and the right name (and perhaps the right colour: Amaranth Red) to guarantee another sales victory.

In short, Page’s Ariels (and possibly 6/1) had shown the way ahead, but Edward Turner’s marketing brilliance and styling flair put the all-important finishing touches to Page’s genius.

In 1938, the 493cc single cylinder Tiger 90 was dropped from the range. With the 5T Speed Twin on the boil, the big Tiger was deemed redundant. What was really needed now was a speedier Speed Twin, a bike for the more sporting rider (as opposed to touring rider); cue the arrival of the Tiger 100.

This new Tiger was to the Speed Twin what Bentley has always been to Rolls Royce. Not that either of these motorcycles ever had such lofty social pretensions or laid claim to bespoke and top quality workmanship.

Far from it.

The Tiger 100 and Speed Twin were everyday bikes built to a good (but not expensively good) standard for everyday people; machines that were as likely to be seen in the hands of the local doctor as the local draper—and ridden by more than a handful of policemen.

But the Tiger 100, with its higher 8:1 compression ratio, slipper pistons, polished internals, quickly detachable silencer end-caps (thereby converting the silencers to megaphones) and optional bronze head was the next move up and a true 100mph machine capable of giving the best of the competition a run for its money.

At £80, the extra five quid sports package was well spent in that it allowed a rider to use his Tiger all week as a general runabout, and then at the weekend scoot on down to whatever race meet was being held and quickly strip down to the bare essentials and get busy winning.

That same year (1938), the Speed Twin saw a minor modification to its cylinder barrels which gained two extra base studs (the T100 was always eight stud). The engine shock absorber was revised and made smoother, and minor revisions were made to items such as the headlamp glass, drive chain lubrication and handlebars.

In 1939, a 5T Speed Twin and Tiger 100 won for Triumph the coveted Maudes Trophy which had been awarded each year since 1923 for the “most meritorious performance” as observed under strict Auto Cycle Union (ACU) conditions.

For 1940, the Speed Twin was altered again in various minor ways to bring it in line with the more refined T100. Changes included a revised fork angle and a larger,
4 gallon fuel tank (up from 3-1/4 gallons).

This was the last year of the girder forked Speed Twin/Tiger 100.

Post war, the bikes started out much the same as before the hostilities, but notable changes included telescopic forks, the repositioning of the dynamo to the front of the engine (previously, the dynamo was at the rear  of the engine coupled with the magneto), and a 19-inch front wheel (replacing the previous 20-inch).

The rear wheel diameter stayed at 19-inches.

To facilitate the new dynamo position, new crankcases were introduced, while other changes were made to the engine including revised oil feeds and a BTH (British Thompson Houston) magneto with automatic advance-and-Retard replacing the previous Lucas unit (the Tiger, note, kept its manual advance and retard).

The compression ratio on the Speed Twin was dropped slightly to 6.5:1 (as opposed to 7:1), and the price had jumped to almost £140, plus a fiver for an optimistic 120mph speedometer.

Through 1947 to 1949, relatively minor revisions were made to the Speed Twin, all of which were carefully controlled by Turner to keep the relentlessly rising price as low as possible. But one very significant and fairly radical option was the introduction of the sprung hub (1948), which offered a couple of inches of rear suspension movement—at the expense of extra weight, mechanical complexity (with all the reliability issues that that entailed), and extra cost.

That same year, three 5Ts were each awarded a gold medal in the first post-war International Six Days Trial (ISDT) held in Italy. The bikes were standard except for alloy heads and barrels (in place of the standard cast iron items) as a concession to the local temperature conditions.

In 1949, the Speed Twin and Tiger 100 were given new petrol tanks and headlamp nacelles (which were enlarged in 1952). The engine compression ratio for the 5T was changed back (up) to 7:1 as better fuel became available. Also, external oil drain pipes (that had been recently deleted) reappeared, and smaller revisions were made throughout the machine.

By now, the bikes were looking far more modern and “clean”, thereby adhering rigidly (no pun intended) to Edward Turner’s principle of neatness at all costs—but always within (financial) reason.

The 1952 “Korean War nickel shortage” saw related changes at Triumph (and with other motorcycle and car manufacturers) in which less chrome was applied and more paint appeared (nickel being an integral part of the quality three stage chrome plating process of copper/nickel/chrome).

In 1953, coil ignition replaced the magneto, and alternator charging replaced the dynamo. This upgrade necessitated the repositioning of the crank mounted shock absorber to the clutch hub (cited by many as a retrograde move in that the available damping movement was reduced by around two-thirds).

In 1954, the era of the rigid frame and sprung hub officially came to an end. But such equipped bikes were still available well into 1955. The new swinging arm frames, meanwhile, offered an (arguably) improved ride, but at the penalty of slightly more weight.

The crankshaft bearings and conrods were upgraded/revised, a two-level twinseat was standardised, and other minor modifications were introduced.

The most significant change for 1956 was the use of 649cc Triumph 6T Thunderbird crankcases; the Thunderbird having been introduced in 1950 priced (then) at almost £195 compared to £185 for the 5T Speed Twin, and £198 for the Tiger 100.

In 1956, a Speed Twin would cost £217; a Tiger 100 £237; and a 6T Thunderbird £227.

The following year, the famous “mouth organ” Triumph badge appeared, and brakes were upgraded to full width hubs. In 1958, the unpopular and shortlived slickshift gearbox, which linked the movement of the gear lever to the clutch release mechanism, was introduced (and was discontinued when the unit construction models appeared). Mudguards were revamped and were made in one piece rather than three pieces.

In 1959, the pre-unit engine was discontinued for the 5T which became the unit construction 5TA (The Tiger 100, meanwhile, remained a pre-unit and kept its original engine dimensions).

The bore and stroke was revised and became 69 x 65.5mm (as opposed to 63mm x 80mm), making the new 5TA a short-stroke engine. The cubic capacity was a little lower now at 490cc, but overall performance was much as before.

The brakes became full width and the frame was revised, notably with a single top frame rail beneath the fuel tank—where previously there were two rails. This alteration meant that the tank itself acted as a stressed member (similar to that of the Triumph Tiger Cub). But the most immediate and obvious difference that year was the large valanced front mudguard and totally enclosed “bathtub” rear panelling.

It was perhaps an inevitable extension of the nacelle concept and gave the bike a neat, clean and tidy profile, but it wasn’t a very popular change, not least because the Speed Twin, once the flagship and darling of the company, no longer looked like at least a semi-sporting machine. Instead, it suddenly looked … well, dull and ordinary—made even more so by the arrival of the elegant and dashing T120 Bonneville.

In 1960, the Tiger 100 became a unit construction engine and shared the 5TA Speed Twin’s engine dimensions. In 1964, the full rear enclosure was rolled back and abbreviated. In 1966, 12 volt electrics were standardised on all twins in the Triumph range. In 1967, the Speed Twin had lost all relevance and was discontinued, while the Tiger 100 was pensioned off the following year.

The final prices were, respectively, £283, and £296.

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