Evolution of A Lightweight Streetfighter

Story by Costa Mouzouris// Photos by Sebas Romero & KTM
July 2 2024

Don’t let the engine size fool you, this ride features big-bike fun.

Since its introduction, the 390 Duke has become KTM’s “bread and butter” bike, outselling all other KTM models. Aside from being a great performer in its category, there’s another reason it’s KTM’s biggest-selling bike: in markets where 125s dominate, it is considered a big motorcycle. Because of this, it has received some big-bike changes for 2024, getting a slew of improvements and tech that you’d normally see on bigger-displacement motorcycles. As we discovered riding it along mountain roads just outside of Almeria, Spain, the 390 Duke has also grown up in the process.

Three Generations

The KTM Duke celebrates its 30th anniversary this year. The 390 Duke isn’t that old, having been introduced in 2013. That first-gen 390 was followed in 2017 by the redesigned second generation, which remained mostly unchanged until last year. This year we get another all-new 390 Duke — 90 per cent new according to its maker.

While the new frame’s geometry is almost the same as before (fork rake is now 24 degrees from 25), it has been designed for increased stability. The biggest telltale of this new frame is the shock location: it is now offset, having been relocated from the centre of the frame to the right. This change redistributes suspension loads to different parts of the frame and swingarm, which improves the torsional stiffness of both items. The external lattice swingarm is more rigid than before, and now features massive bracing and is curved on the shock side. A new die-cast aluminum subframe replaces the former steel-trellis unit, and has been designed to lower the seat from 830 mm to 820 mm; an optional low seat drops that to 800 mm. The wheelbase is unchanged at 1,357 mm.

Despite its sub-400 cc displacement (just barely), the 390 Duke is equipped with adjustable WP Apex suspension. A 43 mm big-piston fork features compression and rebound damping adjustability that is separated between the fork legs, with five clicks of adjustment each.

The shock is adjustable for spring preload and rebound damping; the latter can be done conveniently using the ignition key, which has a flat-blade tip. The damping adjustments have been calibrated to make a noticeable difference with every click. Another change that has improved suspension compliance is a reduction in unsprung weight through new, lighter wheels that weigh 4.3 kg less than before. Sticky Michelin Power 6 radials are mounted to those wheels.

New Single

The 390 Duke has a completely new, lighter, liquid-cooled single that has a 4 mm longer stroke, at 64 mm (bore remains at 89 mm), which increases displacement to 399 cc from 373. Like the previous model, ride-by-wire fuel injection is provided by Bosch. The added displacement bumps engine output to 45 horsepower and 28.8 lb.-ft. of torque, up from 43 hp and 27 lb.-ft. The longer stroke makes the engine…

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