KTM 125 Duke [2017–2020] Review: The Pocket-Sized Streetfighter That Thinks It’s a Superbike

Introduction

The KTM 125 Duke isn’t just a motorcycle—it’s a declaration of intent. Designed for riders constrained by A1 license regulations but unwilling to compromise on adrenaline, this pint-sized streetfighter punches far above its weight. From 2017 to 2020, KTM refined this model into a machine that feels less like an entry-level bike and more like a scaled-down superbike. After spending a day threading it through city traffic and carving backroads, one thing becomes clear: the 125 Duke is a masterclass in balancing youthful exuberance with grown-up engineering.

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Design & Ergonomics: Big Bike Attitude in a Compact Package

The KTM 125 Duke’s design language screams aggression. That angular LED headlight—borrowed from its hulking sibling, the 1290 Super Duke R—glares at the road like a predator. The steel trellis frame, finished in KTM’s signature orange, isn’t just structural art; it’s a flex of engineering confidence. Even the 13.4-liter fuel tank (3.54 US gallons) mimics the muscular contours of larger KTMs, though its narrow profile keeps the bike accessible for shorter riders.

Standout Features:
- LED Lighting: The full-LED setup isn’t just for show. The headlight throws a crisp, wide beam, while the 20-LED parking light ensures visibility in urban chaos.
- Color Options: White and Orange schemes dominate, with black accents adding a touch of menace. Pre-2020 models occasionally featured blacked-out wheels for extra attitude.
- Ergonomics: The 830 mm (32.7") seat height feels taller than some rivals, but the narrow frame lets most riders plant both feet. The upright riding position strikes a rare balance—commuter-friendly yet sporty enough to encourage cornering antics.

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Engine & Performance: Small Displacement, Big Personality

Don’t let the 125cc badge fool you. The liquid-cooled, DOHC single-cylinder engine is a jewel. With 15 HP (11 kW) peaking at 10,500 RPM and 12 Nm (8.85 lb-ft) of torque arriving at 8,000 RPM, it’s tuned for urgency rather than raw speed. The redline? A screaming 11,500 RPM.

Key Highlights:
- Fuel Injection: Bosch’s system delivers crisp throttle response. There’s no carbureted lethargy here—just instant punch off idle.
- 6-Speed Gearbox: Unlike many 125cc bikes stuck with 5 gears, the Duke’s close-ratio ’box lets you chase every last RPM. Highway cruising at 100 km/h (62 mph) is feasible in 6th, though vibrations creep in past 90 km/h (56 mph).
- Fuel Efficiency: 2.42 L/100 km (97.2 MPG) is achievable with restraint. But let’s be honest—you’ll rarely see those numbers.

Real-World Riding:
The Duke thrives in urban environments. From 0-60 km/h (0-37 mph), it feels quicker than its 15 HP suggests, thanks to a 137 kg (302 lb) dry weight. The engine’s character is raspy and eager, goading you to wring it out. On twisty roads, keeping it above 7,000 RPM unlocks a satisfying surge, though overtaking at highway speeds requires patience.

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Chassis & Handling: A Miniature Supermoto

KTM’s dirtbike DNA shines here. The steel trellis frame and WP suspension—43 mm USD forks up front, monoshock out back—are overkill for a 125cc bike, and that’s the point.

Suspension Setup:
- Front: 142 mm (5.6") of travel with preload adjustability. Stiff enough for aggressive cornering, yet compliant over potholes.
- Rear: 150 mm (5.9") travel monoshock. Preload adjustment accommodates passengers or luggage, though the Duke is best enjoyed solo.

Geometry & Agility:
With a 25° rake and 1357 mm (53.4") wheelbase, the Duke flicks into corners like a trials bike. The 110/70-17 front and 150/60-17 Metzeler or Maxxis tires offer tenacious grip, letting you scrape pegs without drama. Ground clearance—185 mm (7.3") on early models—is generous, though later variants sacrificed 10 mm for stability.

Braking:
- Front: A 300 mm disc bitten by a radial 4-piston caliper. Feedback is telepathic, and Bosch ABS intervenes smoothly.
- Rear: 230 mm disc with a single-piston caliper. ABS can’t be disabled on earlier models—a frustration for stoppie enthusiasts.

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Technology & Features: Class-Leading Gadgetry

The 125 Duke shames bigger bikes with its tech suite:
- TFT Display: A full-color 5-inch dash dominates the cockpit. It’s customizable, with gear indicator, fuel economy stats, and a rev-bar that glows orange near redline.
- KTM My Ride: An optional module pairs your smartphone for music control and call management. Gimmicky? Maybe. But it beats duct-taping your phone to the bars.
- ABS: Bosch’s 9MB two-channel system (pre-2020) became single-channel in later years. Purists grumbled, but new riders appreciated the safety net.

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Competition: How the Duke Stacks Up

1. Yamaha MT-125:
- Pros: Slightly comfier seat, smoother engine.
- Cons: Softer suspension, no TFT display. The MT feels like a commuter; the Duke feels like a toy you’ll never outgrow.

2. Honda CB125R:
- Pros: Retro styling, Honda reliability.
- Cons: 14.7 HP engine lacks the Duke’s top-end zest. Handling is more sedate.

3. Suzuki GSX-S125:
- Pros: Fuel efficiency, lower seat height.
- Cons: Budget suspension, dated LCD dash.

Verdict: The Duke dominates in tech and handling but demands a premium in maintenance costs. It’s the choice for riders prioritizing fun over frugality.

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Maintenance: Keeping the Beast Alive

The 125 Duke isn’t high-maintenance, but it rewards meticulous care:
- Valve Adjustments: Every 10,000 km (6,200 miles). Intake: 0.08–0.12 mm (0.003–0.005"), exhaust: 0.13–0.17 mm (0.005–0.007"). DIY-friendly with shims.
- Oil Changes: 1.5L of 10W-40 or 15W-50 semi-synthetic every 5,000 km (3,100 miles). Skip cheap oils—this engine hates sludge.
- Chain Care: The 520 X-ring chain needs cleaning every 500 km (310 miles). MOTOPARTS.store’s chain kits include a brush and lube.
- Tire Pressures: 2.0 bar (29 psi) front, 2.2 bar (32 psi) rear for solo rides.

Upgrade Recommendations:
- Exhaust: Swap the stock can for an Akrapovič slip-on. Gains are minimal, but the soundtrack is addictive.
- Crash Protection: Axle-mounted bungs save costly repairs during parking lot tip-overs.
- Sprockets: -1 tooth front/+2 rear sharpens acceleration for urban warfare.

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Conclusion: The 125cc Benchmark

The KTM 125 Duke isn’t just a starter bike—it’s a masterclass in how to make small-displacement thrilling. Yes, its suspension is stiffer than a caffeine-loaded accountant, and the seat could double as a medieval torture device after hour two. But these quirks only endear it to riders craving authenticity. For new motorcyclists, it’s a bike that teaches you to ride, not just commute. For veterans, it’s a reminder of why you fell in love with two wheels.

Ready to make yours even sharper? MOTOPARTS.store has everything from performance sprockets to Duke-tested riding gear. Because even perfection has room for upgrades.

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Specifications sheet

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