Triumph’s new Bonneville T40: Half the cylinders, all the style?

Triumph has done something rather clever. It’s taken one of the most famous names in motorcycling, removed a cylinder, reduced the engine to 400cc and created a Bonneville that could appeal to a whole new generation. But is it really a Bonneville?

There are certain things in motorcycling that ought to be left alone. The sound of a big British parallel twin, for example. The shape of a proper petrol tank. And the idea that a Triumph Bonneville should have two cylinders, because that’s what made the original such a wonderful motorcycle in the first place.

Well, Triumph has just thrown that last rule out of the window.

Meet the new Bonneville T40 and T40 Black. They look like Bonnevilles, carry the famous name and have all the traditional styling cues. But underneath that beautifully shaped petrol tank is a 400cc single-cylinder engine.

A single-cylinder Bonneville. Good grief.

Before the purists start writing furious letters to Hinckley, however, it’s worth remembering that Triumph knows a thing or two about making motorcycles people actually want to buy. Its 400cc range, developed in partnership with Indian manufacturer Bajaj, has already sold more than 60,000 motorcycles across over 50 countries.

And the new T40 might just be the most appealing of the lot.

Looking the part

First, the styling. Triumph has resisted the temptation to create some sort of futuristic retro hybrid, which is a relief. Instead, the T40 has a proper teardrop petrol tank, rubber knee grips, a round headlight, long mudguards, wire-spoked wheels and twin rear shock absorbers.

There’s even a peashooter exhaust silencer. One of those lovely details that makes a motorcycle look right before you’ve even started the engine.

The tank carries the traditional three-bar Triumph badge and hand-painted coach lining. The engine has machined cooling fins and brushed aluminium covers, while the cables and hoses have been tucked away to preserve the classic appearance.

In other words, someone in Triumph’s design department has been paying attention.

The standard T40 comes in three two-tone colour schemes, including a particularly cheerful Meriden Blue and Tangerine Orange combination. The T40 Black takes a darker approach, with matt grey and black paint, black engine casings and a blacked-out exhaust.

Personally, I’d take the traditional version. A classic Triumph should have a little chrome and colour. Otherwise you might as well paint everything black and pretend you’re auditioning for a motorcycle gang.

The missing cylinder

The engine is the interesting bit.

It’s based on Triumph’s liquid-cooled 400cc TR Series single, but with a revised cylinder head and a special tune intended to give the T40 more of that relaxed Bonneville character.

Power is 32 PS at 7,000rpm, with 36Nm of torque arriving at 5,000rpm.

Those figures aren’t going to frighten anyone riding a Speed Triple, but that’s rather missing the point.

The original Bonneville wasn’t loved simply because it was fast. It was loved because it had character, looked magnificent and made ordinary journeys feel like an occasion.

Triumph says the new engine delivers its torque lower down the rev range, with a distinctive exhaust note and slower idle speed to give it a more relaxed feel.

Whether a modern liquid-cooled single can reproduce anything approaching the charm of a traditional British twin remains to be seen. There is, after all, a fundamental difference between the rhythmic throb of two pistons and the determined thump of one.

But singles can be tremendous fun. Ask anyone who’s ridden a Yamaha SR500 or an old BSA Gold Star.

And 32 PS is quite enough to enjoy yourself on a twisting British B-road without requiring a conversation with the local magistrate afterwards.

More electronics than Apollo 11

Here’s where things become slightly ridiculous.

The T40 might look like something from 1965, but its electronics belong firmly in the 21st century.

There’s a four-inch circular TFT display, full smartphone connectivity, map navigation, cruise control, five riding modes, cornering ABS and lean-sensitive traction control.

Five riding modes. On a 400cc single.

Back in the day, you had two riding modes: running properly and refusing to start.

There’s even a Heritage Mode for the display, which makes the modern screen resemble a traditional analogue instrument. A digital computer pretending to be an old-fashioned speedometer. You couldn’t make it up.

Still, much of this equipment is genuinely useful. Proper navigation is welcome, cruise control makes longer journeys easier and cornering ABS provides an extra safety margin.

Whether anyone needs five different electronic settings to control 32 horsepower is another matter entirely.

A proper everyday motorcycle?

The T40 has an upright riding position, a traditional bench seat and a relatively low 790mm seat height. An optional lower seat reduces that to 770mm.

The wheels are 18 inches at the front and 17 inches at the rear, with lightweight aluminium rims and steel spokes.

There’s a centre stand as standard, too. Hurrah. A genuinely useful piece of equipment that seems to have disappeared from far too many modern motorcycles.

Triumph quotes a ready-to-ride weight of 191kg, which is worth noting. That’s not especially light for a 400cc single, although the low seat and relaxed riding position should help make it manageable.

Service intervals are a generous 10,000 miles, and both versions are A2 licence-compliant.

This is clearly intended to be a motorcycle you can ride every day, rather than something that spends its life being polished in the garage and taken out for a Sunday morning run to the nearest café.

And that’s no bad thing.

So is it a real Bonneville?

This is the question that will divide Triumph enthusiasts.

For some, the Bonneville name belongs exclusively to parallel twins. The original T120 was one of the great motorcycles of the 1960s, a machine that combined performance, style and that unmistakable British twin-cylinder character.

Take away the second cylinder and, arguably, you’ve taken away something fundamental.

But there’s another way of looking at it.

The Bonneville was never meant to be an expensive collector’s toy. It was a desirable, usable motorcycle that ordinary enthusiasts could aspire to own.

The new T40 could bring some of that spirit back, particularly for younger riders who want classic styling without the expense, weight or power of a larger machine.

And there’s something rather appealing about a straightforward 400cc motorcycle that looks good, sounds interesting and doesn’t require you to ride at absurd speeds to enjoy yourself.

Triumph hasn’t announced UK prices yet. Those are due in early 2027, with the first motorcycles expected in dealerships in spring.

Price will be crucial. If Triumph gets it right, the T40 could become one of the most attractive small-capacity retro motorcycles on the market.

Kickstart & Magneto verdict

I’m not entirely convinced that a Bonneville should have only one cylinder. But I am convinced that the world needs more motorcycles like this.

Machines that are attractive, accessible, enjoyable and don’t demand superbike levels of commitment every time you open the garage door.

The T40 has the looks, the heritage and what appears to be a sensible engine specification. Some of the electronics seem gloriously excessive, but at least Triumph hasn’t forgotten the importance of a proper petrol tank, wire wheels and a comfortable seat.

The real test will come when we ride one.

If it handles well, has a bit of character and makes you smile every time you start it, then perhaps the number of cylinders doesn’t matter quite as much as we thought.

Just don’t expect it to sound like a 1960s T120.

That would be asking for a miracle.

Triumph Bonneville T40 – Fast facts

Source: Triumph Motorcycles, October 2026. Riding impressions are editorial expectations, not the result of a road test.