If triples are so good, why is only Triumph still making them?

Think triple, think Triumph. No other firm makes bikes with three cylinders, but the British firm has a whole slew of them in it’s line-up, including the Legend, Thunderbird, Adventurer, Tiger, Trophy, Daytona, Sprint ST, Sprint RS and, of course, Speed Triple. But being the only modern, mainstream manufacturer of triples until Benelli’s Tornado goes on sale is just how Triumph likes it. Triples have always been the mark of a bike that’s a little removed from the norm, and Triumph has settled on the triple thanks to the legend surrounding what were arguably the first ever volume production superbikes – the 1960s Triumph Trident and its in-house contemporary, the BSA Rocket.

At a time when twin-cylinder bikes were de rigeur, these triples were sensational. Just not quite sensational enough to match Honda’s four-cylinder CB750 when it emerged in the same year – 1969 – as the Trident’s UK launch.

But let’s forget twins and four-cylinders four now. Twins vibrate a lot, and fours are just too smooth for some tastes. The obvious in between stage is the triple, chosen throughout the history of motorcycling for no better reasons than its ability to produce more power than the traditional twins of days gone by.

Now things have gone full circle, and if you want something a bit different, with a more distinctive exhaust note than a four-cylinder, you can go for a V-twin or one of Triumph’s many triples.

History of the triple:

It might be Triumph who are best known for triples now, but they weren’t the first to try three cylinders by any means. It was Moto Guzzi who had the first go at it, in 1932, with a 500cc triple engine in a luxury tourer. It wasn’t particularly fast, but it was seriously expensive, so it didn’t last long. Moto Guzzi stuck with the triple a while longer, though, for a sophisticated supercharged competition engine that was raced at Genoa in 1940. Note the date – the Second World War halted development.

At the same time, Yorkshire-based Scott were taking their traditional two-stroke engines one step further, with a two-stroke triple 750 that was exhibited at the 1934 Olympia Show. Very few were produced, although it wouldn’t be the last showing for a two-stroke triple…

In Germany, during the early 1950s, DKW raced a bizarre two-stroke triple of sorts, with reasonable success. Its central cylinder faced forward, almost at right angles to the outer cylinders, and it acted as a supercharger rather than a conventional third cylinder, compressing the air-fuel mixture to force-feed the other two.

It wasn’t until 1963 that Triumph started on their first triple. Little did they know that MV Agusta were working on a triple as well. Even in its first year, the 349cc MV Agusta triple was winning races, and it was later made into a 500. In that form it would pull to 170mph, and often went up against the BSA and Triumph 750 triples.

The Brit bikes came about in the same way that most triples came about. The staple diet of twin-cylinders was wearing thin, and riders were looking for more power and less vibration, especially in the crucial American market. BSA and Triumph had been amalgamated in 1952, and relied on their archaic twins.

Early attempts to enlarge the twins to 750cc simply resulted in excessive vibration and much-reduced reliability, so the obvious answer was to add a cylinder – the Triumph Trident and the BSA Rocket 3 were born. They weren’t enough to revive the dying Brit bike industry in the heady days of the early 1970s though.

So it was left to the rest of the world to go triple mad. First Kawasaki and Suzuki built two-stroke triples, then Yamaha produced the shaft-drive XS750 four-stroke triple, while Laverda came out with the brutish Jota triple. At first they were novel, but as four-cylinder superbikes improved, and became more reliable and affordable, bikers were lured away. There were few better penis extensions than a bike with four cylinders that would rev to 10,000rpm…

Pros and cons of a triple:

To hear a triple is to understand one of the greatest advantages of the three-cylinder engine – the lovely sound it makes. If you waver between appreciation of the gruff, slightly agricultural chug-a-chug of the twin, and the high-pitched screaming of the four, then the distinctive growl of the triple could be for you.

In most other ways, the triple hits the middle ground too. It doesn’t vibrate as much as a twin, but it vibrates more than a four-cylinder. The reason is quite simple – the amount of vibration increases as pistons size increases, and for a given size of engine, a four-cylinder is going to have smaller, lighter pistons than a triple, which in turn is going to have smaller and lighter pistons hurtling up and down than a twin.

Just as importantly, the shock of a piston reaching the top of its travel, stopping, and then going the other way, is evened out by extra pistons travelling to the bottom of their travel. The more pistons balancing each other out, the smoother the engine.

Then there’s size. Four cylinders across the frame is always going to be wide, which means the engine can’t be as low in the frame as it should be for ideal weight distribution, because a low, wide engine would compromise cornering ground clearance. A twin is lovely and narrow, especially a V-twin – but the compromise is the triple again.

In the days of motorcycle frames with a single downtube in front of the engine, the middle cylinder’s exhaust tended to be a problem, because it needed to be exactly where the downtube was. But better frame designs, with twin downtubes, or no downtubes at all, using the engine as a stressed member, eliminated that problem.

Cooling the central cylinder was an early hurdle too, when manufacturers were more used to twins, with either cylinder exposed to lots of lovely cool air on each side of the engine. But water-cooling’s sorted that out – it’s usually a necessary requirement lately anyway, to produce a quiet enough engine to get through noise regulations.

There’s little else to worry about with a triple other than whether you want one or not. It’s not like you don’t know where to go to buy one…

The Future:

Triumph is riding high on its triples. Sure, the TT600 is a four-cylinder, which Triumph have spent a lot of money on, but sales have flopped. That’s likely to encourage Triumph to stick with its triple rather than trying to compete on equal terms with the Japanese.

Like Ducati, Triumph are doing well on the current trend towards bikes that rely more on character than ultimate performance, and the triple delivers character in big fat chunks. How long before the Japanese follow suit, though? They’ve built such good V-twins that the Italians, like Cagiva, are using Oriental engines now. Anything unusual and distinctive is going to do well over the next five years.