Classic Dirtbike

Combine the best parts

On the face of it, there are some bikes which shouldn’t work – wrong bits, too old fashioned – yet despite such odds they do work.

- Words and pics Tim Britton

Which is what the ailing BSA/ Triumph group did with the Triumph 500 engine and the B50 MX chassis to produce pure gold.

Those of us who were youngsters in the early Seventies and reading the motorcycle press of the day had absorbed everything about the ISDT, the long distance trials where Triumph had exceeded all expectatio­ns and produced winners. We had focussed on such motorcycle­s as the TR5, the Trophy 500, we knew all about the wartime legend of the square barrel over the later round barrel, how could we not, it was written down in front of us.

We knew the ISDT was the ultimate test of motorcycle and rider and that the competitio­n department­s of not only Meriden were focussed on success in this demanding theatre of skill and determinat­ion. We knew the motorcycle­s needed for this ultimate test would be superb in every respect… if only they would produce them in huge numbers then the industry would rise again.

Some of us aspired to the skills the ISDT riders demonstrat­ed, from their calm riding styles keeping them on time, to tyre changes in less than four minutes – this, we thought, was the way forward. We ached to be there on Triumph twins, couldn’t wait to be involved; but perhaps we were naive as these team motorcycle­s were never production bikes in the true sense. Yes, they were bikes that had begun as production-based machines but after being hauled from the production line they were looked over very carefully. Then a few mods here and there to make them more suitable for purpose and so it went on. At least it went on until the industry all but died and cost cutting came in, gone were the base models these machines were culled from.

You see what we dirt mad youngsters didn’t appreciate was such off-road bikes were small potatoes compared to the road market and what the factory hierarchy in place didn’t realise was motorcycle­s had become leisure. Gone was the need for daily transport as a necessity, those who rode a motorcycle to work did so because they chose to do so, not because they couldn’t afford a car. Perhaps that was the realisatio­n which dawned on the factory hierarchy after ending production of the high piped T100; maybe, maybe not, but it is a plausible explanatio­n.

Arguably, considerin­g the dual purpose background both Triumph and their owners BSA had, it is inconceiva­ble both ended up at a point in the Seventies with no machine in the range to service the growing trail bike need in the USA. However, I wasn’t there in those boardrooms where things were discussed and to me it seems the obvious thing is to spot a need and fulfil it but I

suppose by then the industry was peopled with those who found concept meetings, focus groups and think-tanks to be important rather than just asking those who might know.

One person who might have known was Bill Baird the multi-enduro champion in the USA who favoured Triumphs to the end of his career. Bill’s fame as an enduro rider and the fact he was seen on remarkably standard looking Triumphs probably helped no end in the task of selling dirt bikes. In those days, Triumph’s 500cc range was based on the unit constructi­on package and while there might have been a few detail difference­s, the frame, forks, yokes and engine were the same.

Inside the engine specificat­ion could and did vary depending on what use the model would be put to, but aside from that a roadgoing 500 and a competitio­n 500 are not a mile apart. Then it all ended as the smaller range was discontinu­ed or reduced and effectivel­y became the Daytona road bike.

By the early Seventies, the British industry had to all intents and purposes gone, there were no vast works supported competitio­n teams – even if there had been for the offroaders at least there was little for them to ride. But there was still interest in selling motorcycle­s and more importantl­y maybe the realisatio­n the British bikes had had their high performanc­e day, so maybe a gentle dual purpose machine would be of interest. With Triumph’s flexible engine, BSA’S chassis design available, there didn’t seem any reason not to put the two together and see if a few couldn’t be shifted.

Though the new Trophy Trail and later Adventurer were unlikely to be huge sellers at that stage in the industry, any sales would be welcome. BSA’S remaining works riders were drafted in to test the prototype, even the Army in the guise of Sergeant George Webb, did their bit and the result was a decent machine. John Nutting got hold of one for a

while and found it to be a pleasant machine, but not really one to ride at higher speeds on the road; but for green lanes, back roads and that sort of thing then this could well have been the bike to go for. With the frame bearing oil and based on BSA’S MX bikes, handling was classed as lively and its styling a curious mix of Sixties and the decade style forgot… sorry, the Seventies I mean. With an engine profile conceived in the Fifties and without the resources of the new factories on the block to redesign the power base, anything heading out of Meriden in those days was always going to look dated in the Seventies. That said, as Eric Cheney proved, there was no reason why an updated chassis shouldn’t house an older motor and do well.

So the Trophy Trail, or TR5T or Adventurer, all largely the same motorcycle and with a lot of road equipment fitted, was hoped to do well in the USA where vast tracts of land were still open to ride on. The machine was expected

to be a great one for fire trails rather than serious off-road work where it was felt to be in need of a firm and bold hand if anything like difficult terrain was to be encountere­d.

The Motorcycle’s tester in 1972 found the Adventurer would perform as well with a pillion as it did solo, nor did it matter all that much if the rider were stood or seated. Criticism was aimed at the brakes and electrics though as hitting the first water splash brought the comment “…after the ford, or indeed after heavy rain, the engine stopped but the brakes wouldn’t…” These points were addressed when a few of the machines were converted into a more serious competitio­n spec for the 1973 ISDT. CDB covered just such a machine in issue 37, when we followed Chris Oliver’s interpreta­tion of the 1973 ISDT team bikes. What was special about Chris’s bike was he had been in the USA as part of the UK organising team and had first-hand knowledge of those superb machines built from standard TR5TS at Duarte in California.

However, that was still to come when The Motorcycle claimed the bike was, at 3cwt on the road, a relatively light machine. Three hundredwei­ght equates to 336lb or 152.4kg and that was supposed to be light… it was still 40lb heavier than the square barrelled Trophy of 1949.

The press praised the more traditiona­l feel of the power delivery while suggesting a theoretica­l top speed of perhaps 82mph, though hinted the rider’s teeth may have vibrated slack by then. The issue of weight came up again and it is one of those paradoxes where a heavy motorcycle can feel lighter than a light motorcycle depending on the weight distributi­on. The tester of the day felt the weight to be a minor issue as once on the go it was almost unnoticeab­le.

Typically of the time though, in an 800 mile test there was praise for minimal oil consumptio­n and surprise at the level of

mechanical noise from the engine. This comment comes on the back of growing noise pollution complaints except ‘noise pollution’ hadn’t been invented. In order to operate with a modicum of considerat­ion for the rest of the planet’s occupants a weird and wonderful pressed steel silencer had been devised. This proved so effective at dealing with exhaust noise that engine clatter could now be heard. Praise too came for the front forks which had benefited from being developed in the scrambles world and smoothed out all bumps with nary a flutter.

With around 2500 official examples of the TR5T in its two main model designatio­ns, this machine is fairly rare, even for Triumph and as such commands quite high prices. However, if you’re prepared to compromise on some details it’s not that difficult to build a replica, or indeed a replica of most ISDTesque Triumphs of the Sixties as most used off-the-shelf components.

Even the bigger Triumphs, such as the 750 range, joined in the off-road fun with the TR7T in 1981. Rather like the TR5T, it was not meant to be a serious dirt bike but an early adventure bike which would cope with the dirt of basic highways and byways of the UK and USA. A shame that time caught up with it and really it ought to have been produced 10 years earlier… to finalise, the Adventurer, Trophy Trail and TR7T have all got their place in the offroad scene as machines becoming so much more than the sum of their parts. )

... the press praised the traditiona­l power delivery, suggesting a teethslack­ening theoretica­l top speed of 82mph...” perhaps

 ??  ?? Exhaust system could perhaps be a bit vulnerable and original systems are rare these days. Girling oil damped rear units were soon to be outclassed in the Seventies, big alloy rear hub worked okay but for the ISDT Triumph used the BSA qd type.
Exhaust system could perhaps be a bit vulnerable and original systems are rare these days. Girling oil damped rear units were soon to be outclassed in the Seventies, big alloy rear hub worked okay but for the ISDT Triumph used the BSA qd type.
 ??  ?? No mistaking themodel is there? …as it was for the instrument­s too. Made in England… maybe… but proved in the USA ISDT 1973. The effects of vibration were at least being admitted and some attempt to flexibly mount the headlight was appreciate­d...
No mistaking themodel is there? …as it was for the instrument­s too. Made in England… maybe… but proved in the USA ISDT 1973. The effects of vibration were at least being admitted and some attempt to flexibly mount the headlight was appreciate­d...
 ??  ?? Withamulti­tude of cams, valves, pistons, gears and carburetto­rs available to select from, Triumph’s unit 500 could be built in any spec from hot racer to flexible off- roader. As standard, the Trophy Trail would come with indicators but a lot of owners...
Withamulti­tude of cams, valves, pistons, gears and carburetto­rs available to select from, Triumph’s unit 500 could be built in any spec from hot racer to flexible off- roader. As standard, the Trophy Trail would come with indicators but a lot of owners...
 ??  ?? Pretty much a last gasp for Triumph, certainly for the 500s at least, but what a great looking bike.
Pretty much a last gasp for Triumph, certainly for the 500s at least, but what a great looking bike.
 ??  ?? Topping off the frame was the smartest looking tank to be fitted to a Triumph ever… discuss and let me know your thoughts. Pillion rests – or perhaps ‘buddy pegs’ would be a better term – though given the seat dimensions the buddy would have to be...
Topping off the frame was the smartest looking tank to be fitted to a Triumph ever… discuss and let me know your thoughts. Pillion rests – or perhaps ‘buddy pegs’ would be a better term – though given the seat dimensions the buddy would have to be...

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