Aprilia SX 125 4T [2018-2022]: A Supermoto That Punches Above Its Weight

Introduction

The Aprilia SX 125 4T is a motorcycle that defies expectations. As part of Aprilia’s lineage of off-road-inspired machines, this 125cc supermotard blends race-bred DNA with street-smart practicality. Designed for riders who crave agility, style, and a taste of Italian engineering, the SX 125 4T straddles the line between beginner-friendly accessibility and genuine sporty thrills. Having spent time with this machine, it’s clear that Aprilia didn’t just build a motorcycle—they crafted an entry point into a lifestyle.

Design & Ergonomics: Rally-Inspired Aggression

The Aprilia SX 125 4T wears its supermotard identity proudly. From the angular bodywork to the high-mounted front fender, every detail screams "ready for action." The twin-tube steel frame (or aluminum perimeter frame on earlier models) isn’t just functional—it’s a visual statement, painted in glossy black to contrast with bold color schemes like Red Raceway and Silver Speedway. The 880 mm (34.6-inch) seat height might intimidate shorter riders, but the narrow profile lets most riders plant at least one foot firmly at stops.

The digital dashboard is a standout feature—a compact, modern unit that’s easy to read mid-corner. It tracks essentials like speed, RPM, fuel level, and even includes a travel diary for logging top speeds and trip distances. Practical touches like the under-seat compartment (perfect for stashing a USB charger) prove Aprilia considered real-world usability.

Engine & Performance: Small Displacement, Big Personality

At the heart of the SX 125 4T lies a 124.8cc liquid-cooled single-cylinder engine tuned to meet Euro 4 and Euro 5 standards. With 15 HP (11 kW) @ 10,000–10,500 RPM and torque ranging between 10.9–11.2 Nm (8–8.3 lb-ft), this isn’t just a commuter engine. The DOHC 4-valve setup and Magneti Marelli fuel injection ensure crisp throttle response, while the 6-speed gearbox encourages aggressive riding.

Twist the throttle, and the SX 125 rewards with a lively character. It’s not about raw speed—the 125cc cap limits top velocity to around 110 km/h (68 mph)—but about how it feels. The engine thrives between 8,000–10,500 RPM, pulling eagerly through winding roads. Fuel efficiency is stellar at 2.6 L/100 km (90.47 mpg), making it ideal for urban commutes or weekend canyon runs.

Handling & Suspension: Lightweight Precision

Weighing 120–134 kg (264–295 lbs), the SX 125 4T is a featherweight champion. The 41 mm USD fork (240 mm/9.4-inch travel) and rear monoshock with progressive linkage (210–265 mm/8.3–10.4-inch travel) are overkill for a 125cc bike—and that’s a good thing. Whether navigating potholed streets or attacking gravel backroads, the suspension soaks up bumps while maintaining razor-sharp feedback.

The 17-inch spoked wheels wrapped in sporty tires (110/80 front, 130/70–150/60 rear) strike a balance between grip and versatility. Flicking the bike into corners requires minimal effort, and the 1,350–1,425 mm (53–56-inch) wheelbase ensures stability at lean. This is a motorcycle that begs to be ridden hard, rewarding riders with telepathic handling.

Braking & Safety: Confidence Inspiring

Aprilia didn’t cut corners here. The 300mm front disc with a floating caliper (and optional ABS on later models) delivers strong, progressive stopping power. The rear 220mm disc is equally capable, though ABS is reserved for the front wheel on Euro 5 variants. The Bosch ABS system includes an anti-rollover mode, a rarity in this segment, which prevents front-wheel lockups during panic braking.

Competition: How Does It Stack Up?

The 125cc supermotard/adventure segment is fiercely competitive. Here’s how the Aprilia holds its ground:

• KTM 125 Duke: The Duke’s 15 HP engine matches the Aprilia, but its steel trellis frame lacks the SX’s premium suspension. The KTM feels more road-oriented, while the Aprilia leans into its rally roots.
• Yamaha MT-125: Yamaha’s naked bike offers a similar powerband but trades off-road prowess for street styling. The MT-125’s LCD dash is flashier, but the Aprilia’s suspension outclasses it.
• Honda CRF125F: Honda’s dirt-focused model trails in power (9.7 HP) but wins in pure off-road capability. The SX 125 bridges the gap between tarmac and trail better.

The Aprilia’s edge lies in its chassis sophistication and visual flair. It’s a bike that looks and feels premium, even beside pricier rivals.

Maintenance: Keeping Your SX 125 4T in Peak Condition

Owning an Aprilia SX 125 4T is relatively straightforward, but attention to key areas ensures longevity:

1. Oil Changes: Use SAE 5W-40 oil (900 ml with filter). Frequent changes every 5,000 km (3,100 miles) are wise for this high-revving engine.
2. Chain Care: The 13/62 sprocket combo and O-ring chain demand regular cleaning and lubrication. A worn chain robs performance on this lightweight machine.
3. Brake Fluid: Flush DOT 4 fluid every two years. Sticky levers? Check for moisture contamination.
4. Cooling System: The 800 ml liquid-cooling system needs periodic checks for leaks, especially after off-road use.

At MOTOPARTS.store, we recommend upgrading to NGK CR9EKB iridium spark plugs for smoother ignition and considering a DNA air filter for improved airflow.

Conclusion: More Than Just a Beginner Bike

The Aprilia SX 125 4T is a motorcycle that transcends its displacement. It’s a gateway to motorcycling passion—equally at home threading through traffic, carving backroads, or even dabbling in light off-roading. While designed for A1 license holders, its playful character and premium components make it a joy for riders of all experience levels.

Yes, the seat is tall, and the power is capped, but these “flaws” fade the moment you crack the throttle. Aprilia’s SX 125 4T isn’t just a bike; it’s an invitation to ride harder, lean deeper, and smile wider. And when you’re ready to personalize it, MOTOPARTS.store has the upgrades to make it truly yours.

Specifications sheet