A Bonneville With One Cylinder

Triumph just put the Bonneville name on a 400cc single. Two versions were announced on October 6, 2026: the Bonneville T40 and the T40 Black. I haven’t ridden either one, so you won’t get a verdict from me here. No “feels like,” no “should be.” What you get is what’s in Triumph’s press release with the adjectives taken out, a list of what the release doesn’t tell you, and at the end the numbers next to four bikes that sit close to it. Every figure for the T40 below is Triumph’s claim.

Here’s where it fits: the T40 is the sixth model on Triumph’s 400cc platform, after the Speed 400, Scrambler 400 X, Scrambler 400 XC, Tracker 400 and Thruxton 400. Triumph says that platform has sold more than 60,000 bikes in over 50 countries. Chief Product Officer Steve Sargent says the aim was “not simply to create a smaller Bonneville,” and he names Bajaj as the development partner.

The Engine Gets Its Own Tune

It’s a liquid-cooled 400cc single from Triumph’s TR Series family. According to Triumph, this version has a revised cylinder head and a tune that’s specific to the Bonneville, with increased torque lower in the rev range. The claimed numbers: 30 bhp at 7,000 rpm and 26.55 lb-ft at 5,000 rpm. Triumph also mentions a lower idle speed.

That’s all the release says about the motor. There’s no bore and stroke, no compression ratio, no gearbox details and no fuel economy figure.

What’s Fitted as Standard

The equipment list is long, so let’s just go through it. There are five riding modes: Road, Rain and Eco, plus two you configure yourself. Each one changes throttle response, traction control and ABS. Cruise control is standard on both versions. ABS and traction control are lean-sensitive; Triumph calls them Optimized Cornering ABS and Optimized Cornering Traction Control.

The instrument is a round 4” color TFT. It connects to your phone for calls and music, and it shows full map navigation through the Triumph Navigation App, which also imports GPX routes. A Heritage Mode swaps the screen layout for an analog-style dial. Lighting is LED all around. You also get self-canceling turn signals, a rear light that flashes under hard braking, a USB-C socket and a center stand.

Wheels, Seat and Weight

The T40 rolls on spoked wheels, 18” in front and 17” in back, with aluminum rims and steel spokes. Out back there are twin shocks. The front brake is a twin-piston caliper with braided lines.

Seat height is 31.1” (790 mm). An accessory low seat takes that down to 30.3” (770 mm). Triumph gives the ready-to-ride weight as 421 lbs and the service interval as 10,000 miles.

And here’s what’s missing: fuel capacity, wheelbase, rake and trail, suspension travel, tire sizes and any word on suspension adjustment. If range or legroom decides it for you, the release can’t help you yet.

T40 or T40 Black

According to Triumph, the difference between the two is finish. The T40 gets chrome mirrors and a chrome grab rail, brushed aluminum heel guards, a brushed steel exhaust and two-tone paint with hand-painted coach lines. The US release speaks of three paint schemes but names two: Meriden Blue with Tangerine Orange, and New England White with Jet Black.

The T40 Black comes in Matt Pewter Grey and Matt Phantom Black. Its rims are gloss black with bright spokes, the engine cases are powder-coated, and the header and muffler are black. Engine, electronics and chassis are the same on both.

Price and Timing

There’s no price. Triumph says it’ll announce pricing in early 2027, and that the first bikes reach dealers beginning in late spring 2027. Accessories at launch include low and comfort seats and saddlebags.

The T40 Next to Four Other Bikes

No ranking here, just the technical differences. The T40 figures are Triumph’s claims; the others come from the NastyNils database.

Start with the Speed 400, because it’s the same platform. It makes 39.4 hp at 8,000 rpm and 28 lb-ft at 6,500 rpm, so the T40’s claimed peak is roughly 8 to 9 hp lower and its torque peak arrives 1,500 rpm earlier. The Speed 400 weighs 375 lbs, which is 46 lbs less, runs 17” wheels at both ends and has the same 31.1” seat height.

The Royal Enfield Classic 350 is an air- and oil-cooled 349cc single with 20 hp at 6,100 rpm, 19.9 lb-ft and a five-speed gearbox. It weighs 430 lbs, 9 lbs more than the T40, sits at 31.7” and runs 19” and 18” wheels.

The Kawasaki W230 is the small one: an air-cooled 233cc single with 17.8 hp and 13.7 lb-ft. At 319 lbs it’s 102 lbs lighter than the T40, and its seat is 29.3” off the ground. The wheel sizes match the T40’s.

Then there’s the Bonneville T100, the 900cc twin that sits above it in Triumph’s own showroom: 64.1 hp, 59 lb-ft at 3,750 rpm and 503 lbs. That’s 82 lbs more than the T40. Seat height and wheel sizes are identical.

What’s still open is the price, the missing chassis numbers and how it rides. The first two should come from Triumph in early 2027. The third one I’ll tell you about once I’ve ridden it.