▲ Some would argue that the Triumph TRW is the coolest looking British military bike ever built. We wouldn't want to get between the warring parties over that one, but the TRW certainly possesses that classic Triumph "cool".
▲ Dave Hitchens is the owner of this particular TRW, and at the time of writing (15th September 2013), it's up for sale at Ace Classics (London) Ltd.
Said Dave, "This bike had been owned by the British Army and was stationed in Germany. It was demobbed in 1975, and was sold off in 1980 with a W registration plate.
"I picked it up from a friend of a friend who had owned it for about seven years. It wasn't running properly and needed some attention to the Solex carburettor. But I decided to fit an Amal monobloc instead (although I've still got the Solex).
"These TRWs are great bikes. They're light and easy to handle, and they've got a great turning circle. I've had mine up to around 65mph, and I think there was a little extra speed in reserve.
"Brakes are reasonably good for a bike of that age. Starting is very easy. And these engines have a clattery sound that you either like or don't.
"I'm selling it now because I also run a couple of other big bikes and I need the power to get around quickly. Consequently, I don't use the TRW as much as I'd like to. But it will be a pity to see it go."
UPDATE. The bike has now sold.
1964 Triumph TRW
Type: Air-cooled sidevalve single
Capacity: 496cc (500cc)
Bore & Stroke: 82mm x 94mm
BHP: 13 @ 4200rpm
Compression ratio: 5:1
Transmission: 4-speed, multi-plate
Brakes: 7-inch drums front and rear
Electrics: 6-volt, magdyno
Front suspension: Girder
Rear suspension: Rigid
Wheels: 3.25 x 19-inch front & rear
Weight: 369lbs (dry)
Maximum speed: 55mph (approximately)
Top Triumph TRW
specialists and links
The BSA WD M20 website
Probably the best military M20 site in the world owned and managed by Dutch BSA M20 expert, Henk Joore.
£15.99 plus P&P
Is the Triumph TRW the thinking man's BSA WM20? That's dangerous talk because the guys who own and love their Birmingham Small Arms M-Series military mounts take their rides pretty seriously and can be a sensitive bunch. And here at Sump we know that because we've got a fabled BSA WM20 in the garage, and every once in a while we chip in some idle comment on Henk Joore's near legendary BSA WM20 forum and more or less talk the talk and walk the walk, etc. So we know what goes down.
Don’t get us wrong. We love our BSA WM20 plenty and have campaigned it for around ten years on the battleroads of England and France. But what with one bike and another, it doesn't get anywhere near the kind of exercise it used to get. And when that happens, you tend to get into a downward spiral of interest and start casting your eyes elsewhere for renewed stimulus, which is why we’ve lately been keeping a close eye on Triumph TRWs and thinking the kind of thoughts that, in the context of a marriage, ultimately leads to shame and disgrace and possibly the divorce courts.
▲ Classic 1950s Triumph lines. This example was built in 1954
Fact is, the Triumph TRW is a compelling proposition for anyone interested in British sidevalves, not least British military sidevalves. A decade ago, they were barely on the radar. You could pick up a reasonable example up for £1200, or less, and you could then pull up at a military bike gathering and nobody would talk to you—except to ask when you were planning on getting a WM20, a Norton 16H, a Norton Big 4 or a Matchless G3/L. Or similar.
So okay, we’re exaggerating a little about being sent to Coventry on your TRW (pun intended). Most military bike riders are a friendly bunch who are invariably intrigued by anything beyond the norm. And the TRW was definitely not the norm in the early part of this century, or the latter part of the century before that. Instead, it was a horse of a very different colour, especially when displayed in RAF livery as opposed to the more usual army green of military bikes.
But all that has changed. Interest in war motorcycles has increased ten fold since we acquired our WM20—thanks partly to the aforementioned website run by Henk Joore. Ten years ago in the UK, there were maybe a few dozen military M20s on the road, and not an awful lot more other ex-army mounts. But today, you can park your military bike in a field beside a tent and a camp fire and it won’t be long before a hundred similar models show up (with the riders in full military despatch dress), and if the weather’s good, you’ll also risk a Spitfire fly past.
▲ Triumph TRW drive/primary side detailing circular alternator access plate. The carburettor fitted to this bike, note, is an Amal and not the original SU or Solex.
So where exactly are the roots of the TRW? Well, you can pick any number of Triumphs right back to the “Trusty” Model H of 1914, perhaps the greatest—or at least best-loved—military Triumph of them all.
But the Triumph 3TW is a more convenient starting point. This was a bike that was born in 1938 in direct response to a UK Ministry of Supply request for a motorcycle of not less than 250cc with a target weight of 250lbs or less. Triumph’s Edward Turner, still smoking with his more or less instant success with the Speed Twin and keen to bolster the firm’s order books, quickly rose to the challenge with the 3TW; a compact 350cc, twin-cylinder engine housed in a rigid frame with girder forks and employing the fuel tank as a stressed member (in later Tiger Cub style). At around 5400 rpm, the overhead valve 3TW, with its cylinder head and rocker boxes cast in one piece, churned out a respectable 17bhp. Thanks to its low weight, it was a reasonably perky three-speed machine, but it needed a fair handful of the throttle to squeeze out the bangs, and nothing much exciting happened until around 3000rpm. This wasn’t ideal because the army also preferred bikes that were fairly quiet and couldn’t be heard more than half a mile away, and 3000rpm, even on a 3TW, makes for a fair racket in still air when the snipers are abroad.
Turner’s original hopes were that the cylinder block and the cylinder head would be made in aluminium alloy. But this was in short supply with the aircraft industry taking all it could get, and so cast iron was employed.
In November 1940, however, Triumph’s Priory Street factory in Coventry was all but obliterated by the Luftwaffe, and that more or less put paid to the 3TW. A limited number had already been delivered to the war office, but in May that year, many—if not most—of these bikes ended up wrecked and abandoned on the shores on Dunkirk.
By May 1942, Triumph (after a brief spell operating from temporary premises in Warwick) had relocated to a new factory near Meriden, Warwickshire and had taken the next step up with a prototype 500cc sidevalve twin, the 5TW.
Bert Hopwood, unquestionably one of the world’s greatest motorcycle engineers (famed for designing the Norton Dominator, and perhaps unfairly overshadowed by Turner) was the man behind this engine. Its most striking feature was the valve chests that face forward into the breeze instead of being located on the right hand side of the engine—an arrangement that was fine for a single cylinder sidevalve engine, but was not very practical for a sidevalve twin.
Therefore, with the 5TW, adjusting the tappets meant working between the exhaust pipes rather than sitting more comfortably at the timing chest. It isn’t a real problem. It’s just different.
▲ Turner's classic nacelle designed to keep the "cockpit" view neat and tidy, Riding position feels a little "sporty", but relaxed.
The “dynamatic” ignition system was by coil and dynamo whereby the dynamo was driven at engine speed, whilst the contact breaker was driven via reduction gear. Also of interest was the fact that the timing gear was chain-driven; something that was more peculiar to Bert Hopwood and Norton than to Triumph which always preferred spur gears.
The pistons were Lo-Ex. The connecting rods were HH56 alloy. The big ends were plain. The compression ratio was 5:1.
The gearbox was four-speed. The frame was rigid. The front fork was telescopic and offered five and a half inches of travel. Overall, this was a very creditable bike with performance and handling superior to anything offered by BSA and Norton. Except that the military had already committed itself to other mounts. Spares for the same had been ordered and stocked. Army mechanics had been trained. Manuals had been printed.
And besides, Triumph was already knocking out three other models for the War Office; the 343cc 3SW (based on the 3S sidevalve); the 493cc 5SW (based on the 5S sidevalve); and the 3HW (based on the 3H OHV). All three bikes were essentially mildly modified civilian Triumphs conscripted for the duration.
What it meant was that there simply wasn’t enough time, tooling, money or development engineers to focus on Hopwood’s 5TW twin and sort out the usual teething problems with a new machine, and so the project was shelved. The military never saw it. But the idea didn’t go away.
However, this bike is unquestionably the most direct antecedent of the TRW. It fitted other War Office requirements in that it was capable of around 60-70mph, weighed no more than 330lbs, could return around 80mpg at 30mph (typical convoy duty speed), had a ground clearance of 6-inches, and could stop in 35 feet from 30mph. However, this 5TW sidevalve was stillborn, and Hopwood moved on to other things.
▲ 7-inch front brake. Adequate in its day. Marginal now
Following the cessation of hostilities, Triumph tried in vain to hawk what might be seen as the second version of the TRW (as differentiated from the 5TW prototype); this bike featuring an all-enclosed drive chain utilising rubber sleeves over the top and bottom chain runs. It appeared at a military vehicle exposition. But the costs were mounting, and the British army was lukewarm about it, and so this project was also shelved.
By the time the TRW (as we know it today) actually appeared, the war was won, but world peace was far from assured. There were looming conflicts that soon resolved themselves into the Greek Civil War (1946), the Malayan Emergency (1948), the Korean War (1950), the Vietnam War (1955) and the Suez Crisis (1956). And the military still needed to keep its equipment up to date as far as that was possible in the generally crippling post-war home market austerity years. So Triumph tried again.
This TRW sidevalve can be viewed as the third version and was launched in 1948. The pre-unit engine dimensions of 63mm x 80mm gave the bike a capacity of 499cc. As with the 5TW, the valves were set transversely across the front of the cylinder block. Excluding prototypes, the TRW was the only twin cylinder sidevalve that Triumph produced—but the firm had explored the idea of a sidevalve twin as far back as 1913 with its 4.5hp, 600cc design with its inlet valves at the rear or the block, and exhaust valves at the front in a fashion similar to later OHV Triumph twins.
Originally, the Triumph TRW was supplied with an SU carburettor, but it was later offered with a Solex Type 26 WH-Z carb.
A crank-mounted Lucas alternator on the drive side (left side) handled the lighting, but a magneto provided the sparks to the plugs. An alternator, incidentally, had been seen on the earlier Triumph 3TW and was the first time that a production motorcycle had ever been fitted with one.
The engine power was transmitted to the four-spring clutch via a single-row primary chain. Brakes are 7-inches front and rear. Tyres are 3.25 x 19 front and 3.50 x 19 rear.
It’s unclear exactly how many TRWs were manufactured by Triumph, but the usual number quoted is 15,539, or “around 16,000”. We’ve heard other numbers, both higher and lower. But 15,000–16,000 will do it for us. For now.
Very few of the bikes were bought by the British army. We’ve heard, in fact, that only twelve were ordered. But other branches of the services took them by the hundred, with the RAF particularly liking them, perhaps because they were generally viewed as very civilised bikes befitting the arguably more "self-important" status of the RAF (to put it bluntly).
The bulk of sales went to Commonwealth countries, where many—or most—TRWs still are. Canada, Australia, New Zealand, South Africa and Pakistan all had their share (not necessarily in that order).
▲ Prototype swinging arm Triumph TRW. Never saw production
In the UK, there’s a 1960 TRW combination at the Royal Army Museum in London. And there are three prototype TRWs at the London Motorcycle Museum, including a swinging arm model that never saw production (images immediately above).
In the 1970s and 1980s, plenty of TRWs were converted to “choppers”, or simply were cannibalised for their frames and forks. Quite a few more were converted into Triumph TR5s which share many of the same components, excluding the engines.
▲ Canvas bags, still functional and surprisingly capacious. We're not sure if these are original or repro, and we don't really care either way. We'd rather ride 'em than count the rivets.
So how many are left? We’ve no idea, but we reckon that there are hundreds rather than thousands, and certainly the TRW register created by Burton Bike Bits is, at the time of writing, boasting around fifty machines.
The TRW was never sold new to the public. It was for forces and other governmental use only. But machines were later sold off secondhand—and were all but given away in the early days.
If you’re buying one, don’t be surprised if the bike has a completely incongruous registration number dating from the 1970s or 1980s. These motorcycles were still in service as late as that, and many owners have declined to opt for age-related number plates (where applicable).
Burton Bike Bits still has plenty of spares for these machines, including complete engines—or, at least, they did have until very recently. But many of the spares, being rare and New Old Stock, ain’t exactly cheap.
▲ Four speed gearbox. Smooth. Efficient. Reliable in service
Owning and riding and owning the TRW
These are invariably described by their owners as “easy going”, “fun”, “docile” and “relaxing”. Which pretty much sums them up. They generally start with an gentle prod on the kickstarter and hum into life and settle into a relaxed lope.
Expect to hear a fair amount of valve and piston clatter until they warm up, and then expect to hear just a little less. Sidevalves, due to poor gas flow, tend to run hot, and TRWs are no exception. But in normal use, they should never overheat.
Clutches are light and fairly smooth. Dab on the gear lever (one down and three up) and the power feeds in easily. Instantly you get a sense of these bikes. They’ll carry you along without much fuss, but there’s no great torque kick in the rear. If you’re looking for that, you might be better off with a single (say, a BSA M20, Norton 16H or a Matchless G3/L or similar). Except that the TRW will cruise at a slightly higher speed at around 55-65mph. You won’t see much more than that, and will probably top out at around 70-72mph. And the pick-up, by the way, is generally better than the aforementioned singles.
Like most Triumph gearboxes, the changes are quick and light and fuss free. Like most bikes of the same era with 7-inch brakes, stopping isn’t exactly awe-inspiring. Except that the TRW is a little lighter than most, and you really do feel it. Also, unlike its girder-forked military rivals, the steering is a treat with a very good turning circle, and plenty of suspension travel. The riding position, with its swept back handlebars, feels right too. There’s absolutely no excitement here either. Just a sober and competent motorcycle going about its rattly business.
But these were also once ISDT mounts that acquitted themselves well, and in 1949 in Wales earned rider Bill Randall a gold medal. True, Bill Randall might have earned the same gold whilst piloting a lot of other bikes. Nevertheless, he did it on a TRW, and with no point penalty.
Fuel consumption is supposedly 80mpg at 30mph, which is unrealistic. You’ll be more likely to see around 45mpg – 55mpg in real world riding—although many TRW owners swear they get much better than that.
Maintaining one of these presents no real problems. Anyone experienced with 1940s and 1950s Triumphs will be able to deal with everything, except perhaps the engines. These share bottom end characteristics with other Triumph twins, but understanding sidevalves is a different skill, especially when it comes to getting the best from them.
But pretty much anyone, with a little care and thought, can deal with whatever the TRW throws at ‘em. It all comes down nut by nut, bolt by bolt. And it all goes back the same way. And being sidevalves, the engines are in fact a little simpler than OHV models.
They burn a little oil, but no more than similar bikes. And like all motorcycles, they like to be kept in use rather than squirreled away at the back of the shed. You could tour with one of these, and you can carry a pillion without too much stress. But you will feel it; not so much in terms of handling, but in terms of oomph—or, being Triumphs, in terms of umph.
Just change the engine oil every 1000-1500 miles, or at least every year. Check the gearbox oil regularly (say every 500-1000 miles). Give the gears half a second longer to engage. Brake a second or two earlier—and watch your distances, and you’ll be okay.
▲ The "W" reg number plates suggests a 1980 bike. This however was simply the date that this TRW was released from the military,
If you’re new to British bikes (having come from, say, Japanese machines), you can forget metric spanners. There’s an old and little know law that gives other British bike riders the right to summarily execute anyone who brings a modern tool anywhere near motorcycles such as this, and that includes the use of metric hammers.
The military equipment for TRWs (just canvas bags and pannier racks, really) is readily available. Most are reproductions, and the quality varies greatly between excellent and rubbish. At the time of writing, we’re not aware of any repro tinware specific to the TRW coming from India (which is currently on a metal bashing binge). But if and when it does appear, watch out. The quality varies, and is improving, but the Indians have some way to go before they reach the standards that were once employed by Triumph.
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