Ducati XDiavel V4 vs Harley-Davidson Fat Boy vs Triumph Rocket 3 Storm GT

POSTED: 09/09/2026

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Ducati XDiavel V4 Harley-Davidson Fat Boy Triumph Rocket 3 Storm GT

Ducati XDiavel V4 vs Harley-Davidson Fat Boy vs Triumph Rocket 3 Storm GT

Three Power Cruisers, Three Very Different Answers

Three motorcycles, three completely different ideas of what a power cruiser should be. The Ducati XDiavel V4, the Harley-Davidson Fat Boy, and the Triumph Rocket 3 Storm GT all sit in roughly the same price bracket and all trade on low-slung style and big-capacity torque, but the engineering behind each one couldn't be more different: a MotoGP-derived V4, a classic air-cooled V-twin, and the largest production motorcycle engine in the world.

This guide is a straight, factual look at what each bike actually offers, so you can weigh up the differences for yourself. There's no declared winner here deliberately, because the right choice depends entirely on what you want from a cruiser. All three are available at Blade Motorcycles, through Blade Ducati, Cheltenham Harley-Davidson, and Blade Triumph.

At a Glance: The Numbers

Specification	Ducati XDiavel V4	Harley-Davidson Fat Boy	Triumph Rocket 3 Storm GT
Engine	1,158cc 90° V4 Granturismo	1,923cc air-cooled 45° V-twin	2,458cc inline-3
Power	168 hp @ 10,750rpm	103 hp @ 5,020rpm	180 bhp @ 7,000rpm
Torque	126 Nm @ 7,500rpm	168 Nm @ 3,000rpm	225 Nm @ 4,000rpm
Weight	229kg (dry)	315kg (running order)	317kg (wet)
Front brakes	Brembo Stylema, 2×330mm, cornering ABS	4-piston fixed caliper, cornering ABS	Brembo Stylema, 2×320mm, cornering ABS
Final drive	Chain	Belt	Shaft
Seat height	770mm	675mm	750mm
Fuel tank	20 litres	18.9 litres	18 litres
Riding modes	Yes, multiple + Ducati Quick Shift	Road, Rain, Sport	Rain, Road, Sport, Rider-configurable
OTR Price at Blade	£26,595	£23,495	£24,595

Prices correct at time of publication for the entry-level colourway of each model. Confirm current OTR pricing and specification with your local Blade dealer.

Ducati XDiavel V4

The Sport Cruiser

A MotoGP-derived engine in a cruiser chassis

The XDiavel V4 is Ducati's argument that a cruiser doesn't have to give up sportsbike performance to get the low, raked-out stance riders want. Its 1,158cc V4 Granturismo engine, a close relative of the unit found in the Multistrada V4, produces 168 hp at 10,750rpm and 126 Nm of torque at 7,500rpm, figures that comfortably outpace both rivals here on outright power. The counter-rotating crankshaft and Twin Pulse firing order are specifically tuned to give the engine a more relaxed, tractable character at low revs despite its sporting pedigree, which matters on a bike designed to be ridden low and laid-back rather than tucked over the tank.

Ducati XDiavel V4 detail: Brembo Stylema brakes and single-sided swingarm

Chassis and technology

At 229kg dry, the XDiavel V4 is significantly lighter than either the Fat Boy or the Rocket 3 Storm GT, and it carries genuine sportsbike-grade hardware to match: a 50mm fully adjustable front fork, a single-sided aluminium swingarm, and Brembo Stylema four-piston front calipers with cornering ABS. The electronics package includes Ducati Traction Control, Ducati Wheelie Control, multiple riding and power modes, a two-way quickshifter, cruise control, and a 6.9-inch TFT display ready for turn-by-turn navigation. It's the most technologically dense of the three bikes here, and the one most clearly related to Ducati's sportsbike range underneath the cruiser bodywork.

Engine	1,158cc liquid-cooled 90° V4 Granturismo
Power	168 hp (124 kW) @ 10,750rpm
Torque	126 Nm @ 7,500rpm
Weight	229kg dry
Front suspension	50mm fully adjustable USD fork, 120mm travel
Rear suspension	Fully adjustable monoshock, single-sided swingarm
Front brakes	Brembo Stylema, 2×330mm discs, cornering ABS
Final drive	Chain
Riding aids	Traction control, wheelie control, cornering ABS, quickshifter, cruise control
Seat height	770mm
Tank	20 litres
Price at Blade	£26,595 OTR

View the XDiavel V4

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Harley-Davidson Fat Boy

The Icon

The steamroller stance, built around a classic V-twin

The Fat Boy needs the least introduction of the three. It's one of the most recognisable silhouettes in motorcycling, built around a wide 160-section front tyre and a huge 240-section rear on solid Lakester cast aluminium wheels, creating the "steamroller stance" Harley-Davidson has been refining since the original launched in 1990. Power comes from the Milwaukee-Eight 117 Custom, a 1,923cc air-cooled 45-degree V-twin producing 103 hp at 5,020rpm and 168 Nm of torque delivered low down at just 3,000rpm. This is the largest capacity engine of the three bikes here, though it's tuned entirely for relaxed, unhurried torque rather than outright top-end power, which is the whole point of the format.

Harley-Davidson Fat Boy detail shot: wide front and rear tyres on Lakester wheels

Style over spec sheet, and no less capable for it

At 675mm, the Fat Boy has by far the lowest seat height in this comparison, making it the most approachable of the three for shorter riders, and belt final drive means none of the maintenance associated with a chain. Standard equipment includes cornering ABS, traction control, Drag-Torque Slip Control, tyre pressure monitoring, cruise control, and selectable Road, Rain and Sport ride modes. It's a simpler electronics package than the Ducati's, deliberately so, in keeping with a bike built around mechanical character and presence rather than outright technology.

Engine	1,923cc air-cooled 45° V-twin, Milwaukee-Eight 117 Custom
Power	103 hp (77 kW) @ 5,020rpm
Torque	168 Nm @ 3,000rpm
Weight	315kg running order
Front suspension	49mm telescopic fork, dual-bending valve
Rear suspension	Hidden coil-over monoshock, hydraulic preload adjustment
Front brakes	4-piston fixed caliper, cornering ABS
Final drive	Belt
Riding aids	Cornering ABS, traction control, DTSCS, TPMS, cruise control
Seat height	675mm
Tank	18.9 litres
Price at Blade	£23,495 OTR

View the Fat Boy

General Enquiry

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Triumph Rocket 3 Storm GT

The Torque Monster

The biggest engine in production motorcycling

Triumph builds the Rocket 3 around a genuinely singular claim: at 2,458cc, its liquid-cooled inline-triple is, according to Triumph, the largest capacity engine ever fitted to a production motorcycle. The figures back up the billing. 180 bhp at 7,000rpm is the highest peak power output of the three bikes here, but it's the torque that defines the Rocket 3's character: 225 Nm at just 4,000rpm, more than either rival, and delivered with the kind of low-down shove that makes the Storm GT feel effortless from a standstill. The GT designation adds a more relaxed, touring-oriented riding position and pillion comfort over the standard Rocket 3, without losing any of that straight-line performance.

Triumph Rocket 3 Storm GT detail shot: Showa suspension and Brembo Stylema brakes

Premium running gear

The Storm GT backs up its headline engine with genuinely high-end components: fully adjustable Showa suspension front and rear, radial Brembo Stylema monobloc calipers on 320mm front discs, and Optimised Cornering ABS. A full aluminium frame helps keep the 317kg wet weight in check for a bike with this much engine, and shaft final drive means low maintenance on a machine most owners will want to cover serious distances on. A TFT instrument pack, selectable Rain, Road, Sport and Rider-configurable ride modes, and an accessory Bluetooth connectivity module round out the package.

Engine	2,458cc liquid-cooled inline-3, DOHC
Power	180 bhp (134 kW) @ 7,000rpm
Torque	225 Nm @ 4,000rpm
Weight	317kg wet
Front suspension	Showa 47mm USD forks, fully adjustable
Rear suspension	Showa piggyback reservoir monoshock, fully adjustable
Front brakes	Brembo Stylema monobloc, 2×320mm discs, cornering ABS
Final drive	Shaft
Riding aids	Optimised Cornering ABS, 4 riding modes
Seat height	750mm
Tank	18 litres
Price at Blade	£24,595 OTR

View the Rocket 3 Storm GT

General Enquiry

Book a Test Ride

What Really Sets Them Apart

Ducati XDiavel V4	Harley-Davidson Fat Boy	Triumph Rocket 3 Storm GT
Sportsbike-derived V4 engine and electronics in a cruiser chassis	The lowest seat height and the most instantly recognisable silhouette	The largest engine and the most torque of any production motorcycle
Lightest of the three by some margin, at 229kg dry	Belt final drive for low ongoing maintenance	Shaft final drive built for covering distance
Most comprehensive electronics package: wheelie control, quickshifter, cruise control	Simplest electronics, built around mechanical character over technology	GT-specific comfort and touring focus over the standard Rocket 3

Which Power Cruiser Is Right for You?

Choose the Ducati XDiavel V4 if…

You want a cruiser that rides like it has a sportsbike hiding underneath it. The XDiavel V4 offers the most power, the lightest weight, and the most sophisticated electronics package of the three, backed by genuine Ducati sportsbike hardware in Brembo Stylema brakes and fully adjustable suspension. It suits riders who want the low, laid-back cruiser stance without giving up performance, cornering ABS, traction control and a quickshifter.

View XDiavel V4 Enquire Now Book a Test Ride

Harley-Davidson Fat Boy: choose this bike

Choose the Harley-Davidson Fat Boy if…

You want the archetype, done properly. The Fat Boy offers the lowest seat height of the three, a genuinely unmistakable presence, and the relaxed, low-rev torque delivery that a classic air-cooled V-twin is built for. It suits riders for whom the sound, the stance and the heritage of a Harley are the whole point, and who want a cruiser that's simple to live with, courtesy of belt drive and straightforward electronics.

View Fat Boy Enquire Now Book a Test Ride

Triumph Rocket 3 Storm GT: choose this bike

Choose the Triumph Rocket 3 Storm GT if…

You want the biggest possible statement of raw torque. Nothing here, or arguably in production motorcycling, matches the Rocket 3's 225 Nm, delivered low down and building into a genuine 180 bhp peak. The Storm GT adds distance-friendly comfort and shaft drive on top, making it suit riders who want maximum straight-line performance and effortless overtaking in a package still built for covering real miles.

View Rocket 3 Storm GT Enquire Now Book a Test Ride

Common Questions

Which is more powerful: the XDiavel V4, Fat Boy or Rocket 3 Storm GT?

The Triumph Rocket 3 Storm GT has the highest peak power at 180 bhp, followed by the Ducati XDiavel V4 at 168 hp, and the Harley-Davidson Fat Boy at 103 hp. On torque, the Rocket 3 Storm GT leads with 225 Nm, ahead of the Fat Boy's 168 Nm and the XDiavel V4's 126 Nm.

How much do they cost in the UK?

At Blade Motorcycles, the Harley-Davidson Fat Boy starts from £23,495 OTR, the Triumph Rocket 3 Storm GT from £24,595 OTR, and the Ducati XDiavel V4 from £26,595 OTR. Prices vary by colourway; contact your local Blade dealer to confirm current pricing.

Which has the lowest seat height?

The Harley-Davidson Fat Boy has the lowest seat height at 675mm, making it the most approachable of the three for shorter riders. The Triumph Rocket 3 Storm GT sits at 750mm and the Ducati XDiavel V4 at 770mm.

What's the difference in final drive between the three?

The Ducati XDiavel V4 uses chain final drive, the Harley-Davidson Fat Boy uses belt drive, and the Triumph Rocket 3 Storm GT uses shaft drive. Each has different maintenance implications: chains need regular cleaning and adjustment, belts need little upkeep, and shaft drive is largely maintenance-free.

Can I test ride all three at Blade Motorcycles?

Yes. All three are available to view and test ride at Blade Motorcycles: the XDiavel V4 at Blade Ducati in Oxford, the Fat Boy at Cheltenham Harley-Davidson, and the Rocket 3 Storm GT at Blade Triumph in Stratford-upon-Avon or Cheltenham.

Come and See Them in Person

Specification sheets only tell you so much with cruisers like these: the riding position, the sound and the sheer physical presence of each bike are things you need to experience for yourself. Blade Motorcycles is one of the few dealer groups in the UK where all three are available across our showrooms.

Blade Ducati

XDiavel V4

Oxford: 01235 466089

View XDiavel V4 Enquire Now Book a Test Ride

Cheltenham Harley-Davodson Motorcycles Dealership

Cheltenham Harley-Davidson

Fat Boy

Cheltenham: 01242 240570

View Fat Boy Enquire Now Book a Test Ride

Blade Triumph

Rocket 3 Storm GT

Stratford: 01789 205149

Cheltenham: 01242 235999

View Rocket 3 Storm GT Enquire Now Book a Test Ride

Finance subject to status. Written quotations available on request. Blade Motor Cycles Limited is an Appointed Representative of Automotive Compliance Ltd, authorised and regulated by the Financial Conduct Authority (FCA No. 497010). Prices correct at time of publication, always confirm current OTR pricing with your local Blade dealer before purchasing.

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