Upcoming Triumph Bonneville 400 seen testing

The Triumph Bonneville 400 has been spotted testing on our roads once again. The latest images show what appears to be a near-production-ready test mule, offering the clearest look yet at the motorcycle’s styling and key hardware ahead of its expected launch.

1. Will use Triumph’s 349cc engine shared with the rest of the ‘400’ range
2. Gets wire-spoke wheels and twin rear shock absorbers
3. Noticeably larger and bulkier than the Speed 400

Triumph Bonneville 400: What we know so far

The Bonneville 400 appears to be much more than a retro-styled Speed 400

When the Triumph Bonneville 400 was first spotted testing earlier this year, it was clear this wouldn’t simply be a Speed 400 with a few retro styling cues. Subsequent sightings confirmed that the bike rides on a revised chassis with a new swingarm and redesigned rear subframe to accommodate its flat, bench-style seat. Together, these changes give the bike a more authentic Bonneville silhouette and proportions closer to rivals such as the Royal Enfield Classic 350.

The bike is noticeably larger and bulkier than the Speed 400. Its bigger fuel tank, longer, more rounded side panels and chunkier front and rear fenders give it greater road presence. Earlier test mules featured chrome-finished engine covers, grab rails and exhaust, while this latest example wears a blacked-out finish for all three. This suggests Triumph is evaluating multiple variants, much like the larger Bonneville T120, which is offered in both standard and T120 Black guises.

Mechanically, the Bonneville 400 is expected to use the same 349cc single-cylinder liquid-cooled engine as the rest of Triumph’s India-built 400 range, albeit likely in a more relaxed state of tune to suit its laid-back modern-classic character. Triumph has also stayed true to the Bonneville formula by equipping the bike with a conventional telescopic fork, twin rear shock absorbers and wire-spoke wheels – a notable departure from the USD fork and alloy wheels found on the Speed 400.

While Triumph is yet to announce an official launch date, it earlier indicated that the Bonneville 400 would arrive in the second half of the year.