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1938 Triumph 5T Speed Twin 500

The 1938 Triumph 5T Speed Twin 500 was a revolutionary motorcycle, it was the birth of the parallel twin.

Most, if not all British twins that followed owed a debt to both Edward Turner and his Triumph 500 Speed Twin. Whilst it was not the first of its kind, it was lighter, narrower and most importantly, far smoother than any of its contemporaries.

So, if you are as keen as I am to find out how the Triumph 500 Speed Twin came to be let’s start by taking a look at the designer, Edward Turner.

Edward Turner 

Edward Turner was fresh out the Merchant Navy in 1920. By 1925 he had built his first motorcycle engine and 1927 saw the first Turner Special Motorcycle.

November 1928 saw Turner recruited by Ariel where shortly after the Ariel Square-Four was born and was the first of many game-changing designs that Turner would be responsible for. 

It would be foolish to skip past the Ariel Square-Four without first acknowledging why that bike was in itself special.

In its essence it was two 2-cylinder engines with across-frame crankshafts that were geared together. Initially it was a 500cc bike but a later redesign, the model ‘4G’ meant the displacement was bumped up to 995cc. 

The bike was the go-to for reliability and cruising, the engine design meant it was practically bulletproof and could happily lug a sidecar all day long. Reliability was the key to the Square-Four’s success as at the time it wasn’t a trait that many motorcycles possessed.   

Turner had entered the world of motorcycle design with a bang and it was only going to get more impressive from there.

1932 Turner began his long affiliation with Triumph and was designated Technical Director, although ‘Chief Buyer’ ‘Head Designer’ ‘General Manager’ and others were title’s that Turner was known to proclaim himself to be. 

Turner was said to be egotistical and both the saviour and curse of the Triumph brand. An example of this was that there was already a ready-made twin in existence when Turner joined Triumph. 

The problem was however, that Val Page was the man behind the design and Turner actively hated the man. Val Page was the man behind the BSA Gold Star and the engine in the Brough Superior SS1000.

Val Page went to work for Ariel and Turner set about his own creation.  

The first task at hand was to address the vibration issues of the single-cylinder designed machines which dominated the market, bar a few V-Twins that were mainly for use with sidecars.  

Bikes were slowly growing in displacement and power output, but this was shooting up the engine speed (RPM) and designers, despite best efforts, were struggling to stop the vibrations that one big piston flying up and down the cylinder caused.

It was causing rider discomfort and engine failure on bikes not capable of dealing with the issue for long periods of time. 

Turner approached the problem by splitting the displacement into two cylinders that rose and fell together on a 360° crankshaft. 

He named the design the Parallel Twin (known synonymously as the Vertical Twin) and the Triumph 500 Speed Twin was born.

Short clip of Edward Turner talking about the Speed Twin

Unfortunately, Ed Turner’s ego and ‘know-all’ attitude would also prove to go against Triumph and this was notable in the development of the Speed Twin. 

Instead of investing in Research and Development for the bikes, Turner led the way in recycling parts from earlier versions and models, refusing to change things because he believed they were good enough as they were. 

It took until 1955 for example before the Speed Twin received a modern swing arm, despite the fact the rigid frame had been un-practical for a long time.

The pre-unit construction of both the 500cc and 650cc engines were known for oil leaks and for a man of impeccable design skills, you would have thought this would have been a priority to fix, especially because the Ariel Square-Four success was built on its reliability.

An absolute classic was with the original design of the Speed Twin, Turner refused to angle the rake that would make for easier handling because it would ruin the look of the lines. 

Turner’s ego would prove to be a constant problem throughout his time with Triumph and the source of much controversy and poor business decisions.

However, the man created the legend so let’s cut him a bit of slack and take a further look at the history of the Speed Twin and the timeline in which it developed. 

Triumph 500 Speed Twin Timeline

1938 The original 500 Speed Twin was the top-of-the-line sports bike but predominantly marketed for touring. It was both faster and smoother than any single on the market and gained a huge fan base. 

It was however, built to match British style at the time and aesthetically didn’t sway too much from the standard; it also used many parts from other Triumph models. 

It was cheap to manufacture in comparison with other bikes of the time and thus had a competitive selling price, which would continue throughout its existence.

1939 Triumph were already increasing the compression (among other things) in an attempt to get more out of the 500cc engine. 

The Triumph Tiger 100 was created from raising the compression ratio in the Speed Twin from 7.2:1 to 8.0:1 for the new bike. The Tiger had the 100 added to its name for the claim of it hitting 100mph as its top speed.

It was the sportier, faster version of the 500 Speed Twin and it was a big hit. Triumph had nailed it by producing two new exciting bikes in 2 years all on the back of Turners vertical twin design. 

1940 The German’s bombed the Triumph factory but this was to have its own silver lining as the British government paid to have the factory rebuilt which was to become the legendary Meriden factory.

1946 Production resumed and Triumph’s competitors all wanted their own ‘vertical twin’ inspired by Turner’s design. BSA, Norton, Matchless and Royal Enfield were all quick to bring out their own similar models. 

The 1946 5T Speed Twin was Triumph’s best seller and restored the company back into financial success following the impact from the war. Quite literally it was the saviour of the Triumph brand. 

It was very much the same as the pre-war model with the exception of a change of forks to modern telescopic forks which greatly improved the bikes handling.

1950 The Speed Twin had taken a back seat to bigger displacement bikes in Triumph’s line up as the demand from the American market in particular was huge for faster bikes and Triumph was leading the race to fill that gap. 

The 500cc engine was bored and stroked out to 649cc for the 650 6T Thunderbird and this was shortly followed by the 650 Tiger T110.  

1951 None of this would have happened however without the first 500 Speed Twin and the 1951 version was still desirable and selling well. It continued to be faster than many motorcycles available at the time but was styled more for practicality than speed, with big fenders and a headlight nacelle. 

1953 The model had been upgraded to a modern alternator system with a battery and coil ignition. 

1954 The 500 Speed Twin was now Triumph’s entry-level twin but still selling fairly well. It retained the original cast iron cylinder block and head with a single carburettor. The model was still pre-unit construction and in its original rigid frame. 

The main difference for the year was a sprung rear hub which was to supposedly cushion bumps on the road. The downside to this was that the springs would wear down quickly and could fail when under constant or hard use. 

It was the cheaper option for Triumph, as their alternative was to replace the frame and that was deemed to be too expensive.

1955 Rigid frame was finally replaced and rear swing arm suspension added.

1959 Saw the 650 Bonneville arrive and the 500cc twins relegated even further. It was during this time that Turner famously claimed Triumph’s to be ‘The World’s Fastest Motorcycles’. 

He wasn’t wrong either. Johnny Allen set the world record in 1955 at 193.3mph for the world’s fastest motorcycle on his Triumph. And in 1956 he set the record again at 214.17mph that stood until 1962.

1961 The Speed Twin had received unit construction and the infamous ‘bath-tub’ styling. The unit construction was rolled out across all of the line-up and certainly beneficial for Triumph’s build quality. 

The ‘bath-tub’ styling however, was a huge fail and quickly dropped. 

1966 Production of the original Triumph Speed Twin finally ended although the 500cc engine would continue to be used until 1973.

2019 Triumph released the new Speed Twin to add to its Modern Classics line-up with a 1200cc engine delivering 96HP, it’s a far cry from the original, but what a way to honour the original speed machine. 


The 5T Speed Twin was met with excitement and during its initial release at the 1937 National Motorcycle Show, the buzz it caused eclipsed other offerings from Norton and Matchless. 

The 1938 Speed Twin had a 6-stud engine and tested by magazines at the time it came out with an average max speed of 94mph and a recorded 107mph quarter mile. It set the bar and only Turner himself had the capabilities to change it. 

The 500 Speed Twin however was intended to be a touring bike and Turner himself was actively against racing it. It is said he caught two employee’s supercharging their own bikes and he watched while he forced them to smash them to pieces. 

Despite this, the fact the bike was capable of such speeds was a testament to the quality of the design Turner had created. 

It could run rings around the Harley and Indian V-Twins at the time. Even so, the American market demanded bigger engines and more power, so Turner responded with the Tiger, Thunderbird and later Bonneville. 

The 500 Speed Twin stood in the line-up of original Triumph’s for such a long period of time because it was built for practicality, it was affordable, and it was fast enough for any rider bar a dedicated racer.

Bud Ekins & Steve McQueen

Bud Ekins and his pal Steve McQueen were just two of many famous Speed Twin owners.

Bud’s 1938 model was up for auction in 2017 for $27,500 but failed to meet the seller’s reserve. 

Ekins was the stuntman and bike fanatic that introduced Steve McQueen to motorcycles and was also the one who completed the historic jump in ‘The Great Escape’. 

McQueen was keen and willing but the studio heads wouldn’t let him, so Ekins stepped up, a folklore tale is that McQueen actually completed the jump behind the studio’s back, off-camera.

In the mid 1970’s Bud Ekins restored his friend Steve McQueens 1938 Triumph 5T Speed Twin. It sold a few years ago in a Las Vegas auction for $175,500

Buying an original Triumph 5T Speed Twin

As a general rule the older the model, the more expensive and harder to find they are. Coveted because they are iconic, owners of early models don’t tend to sell.

Car and Classic in the UK have two 1939 models for sale for £19,999 and £24,999 respectively.  

the Triumph 5T speed twin released 1938
This stunning 1938 Speed Twin was sold by Bonhams in Las Vegas for $42,550 back in 2019

The good news however, is that the bikes that do come up tend to be well looked after. They aren’t cheap but generally are well preserved and worthy of the investment.

It is possible to find early models for around £15,000 in the UK or $13,000 in the US but bear in mind at this price point it is unlikely the bike is completely original and will likely have been restored at some point. 

While browsing there seemed to be a fair few late 50’s models for sale in the UK all priced around £5,500 in good condition. 

So, there is a definite price drop in the post war Speed Twins and an increase in availability. For someone who wants an early 500 Speed Twin but can’t justify the Mk1 expense this may prove to be a good alternative. 

Triumph 5T Speed Twin Restoration

As with the price discrepancy in buying an original 500 Speed Twin there is a discrepancy in parts between the pre-war and post war models. 

The easiest restoration project would be to find a donor 500 Speed Twin from the 1950’s era as parts are in abundance and priced reasonably. 

Expect a good bike to set you back between $3,500-5,000 initially.

Parts from the 500 Speed Twin during this time were quite interchangeable between other models in the Triumph range and therefore there are more parts on the market as well as quite a large replica parts market. 

Some examples of prices are as follows:

  • £6.25 Set of clutch springs
  • £14.95 Pre-unit Screw kits
  • £22.50 Sump Plate 
  • $225.50 Tank
  • $32.95 Handlebar Double Throttle Control 

British restorers will find parts easier to find than their American counterparts, but many of the sites that sell relevant parts will ship to worldwide.

Is an original Triumph 5T a Good Investment? 

Investing in a 1938 or 1939 model is without a doubt a really solid investment. 

Value will only continue to increase as time goes on and there will continue to be a demand from collectors who want to own a very important piece of not only Triumph but motorcycle history. 

1950’s -70’s models are perfect buy to ride classics. I wouldn’t expect the value to increase dramatically anytime soon, simply on the basis that there were more produced and therefore, more of them still around. You can expect to buy one and sell a few years later without making any loss.


The Triumph 5T Speed Twin 500 is one of the few motorcycle’s that not only deserves its iconic status but also lives up to it. British and the motorcycling world in general may well have looked very different today if Edward Turner hadn’t worked his magic and produced the original Triumph 5T back in 1937.

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