Aprilia SX 125 2021 — Specifications

When Aprilia resurrected the SX 125 in 2018 after a few years of absence, no one expected it to become a benchmark in its category. Yet, the 2021 Aprilia SX 125 pushes the bar even further, with a substantial engine revision to secure Euro5 certification while gaining character.

The initial impression is one of project coherence. The machine weighs 120 kg fully fueled, a lightness that is justified as soon as you start handling it in the city or on a supermotard circuit. The 880 mm seat may seem high for smaller riders, but this choice is not arbitrary: it places the rider in an active position, with bent legs, ready to play with the lean angle and the brake. Faced with a Honda MSX 125 or a KTM Duke 125, the SX clearly claims a more radical positioning, less versatile, more focused on pure sensations.

The 124.8 cc four-stroke single-cylinder engine has been deeply revised for this model year. New combustion chamber, iridium spark plug, reworked camshafts, redesigned intake and exhaust system, latest-generation Magneti-Marelli MIUG4 ECU. The result? An engine restricted to 15 horsepower at 10,500 rpm, as required by law for the A1 license, with a torque of 22.2 Nm available from 8000 rpm. It’s not brute power, but the usable range is more direct than before, less hollow at low RPM. Those considering an Aprilia SX 125 derestriction would be better off abstaining: the machine's appeal lies in its lightness and chassis, not in a race for maximum speed, which is limited to 120 km/h anyway.

The cycle part, just so, constitutes the real selling argument. The 40 mm inverted fork and the hydraulic mono-shock offer generous travel, designed to swallow bumps on a supermotard as much as poorly maintained Parisian sidewalks. The 17-inch spoked rims are fitted with 110/70 tires at the front and 150/60 at the rear, sporty dimensions that transform every turn into an opportunity. The front brake, a 300 mm floating disc caliper, benefits from ABS with rear wheel lift-up function. This technical detail, very rare on a 125 cc, concretely changes the way you approach hard braking. The Aprilia SX 125 reviews from those who have ridden it consistently mention this point.

The technical specifications of the Aprilia SX 125 mention a perimeter steel frame, a contained wheelbase of 1350 mm and a 10-liter tank. The whole remains compact, lively, designed for a rider who wants to play rather than travel. It's not a machine for long raids or highways: it's a precision weapon for sporty urban riders or young A1 license holders who refuse to settle for a scooter disguised as a motorcycle. At 4099 euros, the Aprilia SX 125 catalog price is in the high-end of the sporty 125 segment, but the electronic equipment and manufacturing quality justify the gap with more affordable competitors.

The cousin RX shares the same mechanical base and chassis, but moves towards off-road with off-road profile wheels. The SX, on the other hand, remains on the tarmac and mixed areas. This platform sharing allows Aprilia to control its costs without sacrificing the specificity of each model. The compact dashboard remembers the maximum speed reached, displays the battery voltage and manages two partial counters. Simple, functional, without frills. The USB socket remains an option, which may annoy in 2021, but it changes nothing about the essential: the Aprilia SX 125 technical specifications speak of a machine designed for riding, not for plugging in.