The RS 125 has a fresh design, more powerful engine, and updated electronics

Aprilia revamped its RS 125 ahead of MY2021 with a number of improvements on its proven eighth-liter platform with a fresh design, newer more powerful plant, and updated electronics. All of this comes on the heels of a quarter-century of racing success to bring a bona fide racebike experience to all those nascent pegdraggers out there. Choose between the base-model RS 125 and its GP Replica variant that brings even more racetrack yummygoodness to the table.

  • 2021 Aprilia RS 125
  • Year:
    2021
  • Make:
  • Model:
  • Engine:
    single cylinder
  • Displacement:
    124 cc
  • Top Speed:
    70 mph (Est.)
  • Price:

2021 Aprilia RS 125 Design

  • Full LED lighting
  • Aggressive RS styling
  • Fully digital instrumentation
  • Optional infotainment package
2021 Aprilia RS 125
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2021 Aprilia RS 125
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2021 Aprilia RS 125
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Built for both track and street, the new RS 125 carries clear genetic markers from its big brothers, the also-new-for-2021 RS 660 and RSV4.

Built for both track and street, the new RS 125 carries clear genetic markers from its big brothers, the also-new-for-2021 RS 660 and RSV4, especially in the front end for the low-drag penetration and genuine race-tastic vibe it provides. Nose-down and tail-up, it looks like a sprinter crouched at the blocks or a predator ready to pounce. The broad cowling panels extend to shift even more visual weight forward to reinforce that all-up-front look.

A trio of recessed LED headlights ride at the tip of the nose with lick-’em stick-’em blinkers mounted abreast. Even though the turn signals are mounted fairly high on the front fairing, they are definitely vulnerable to being wiped off in a drop or a slide which is less than ideal for a bike that is most likely to be ridden by inexperienced riders.

The bubble-screen imparts even more big-boy bike functionality to the mix between tall mirror standoffs that I expect are easily removed and their holes plugged ahead of track days even though the factory doesn’t explicitly say so. Same with the mudguard/plateholder out back. Behind the bubble rides an all-new digital instrument display that comes backlit in a choice between a white glow and a light blue to allow you to dial in for the ambient light conditions and personal preference.

Clip-on handlebars bear directly on the upper fork tubes just below the upper tripleclamp to encourage and enable an aggressive riding posture with set-back footpegs to define the rider’s triangle. The bars come 18 mm higher than before to increase comfort.

As a bonus, since your hands are so close to the steering axis, you can count on honest feedback and precise inputs for your kneedragging shenanigans. The 3.8 gallon fuel tank contributes a tall hump in the flyline ahead of a deep swale that pulls the pilot down into the machine, rather than leaving you sort of perched on top for a level of man-machine integration that is hard to improve upon. In keeping with its dual-purpose design, a barely-there pillion pad and fold-up footpegs come stock to accommodate your very brave passenger if you like to share the fun with a friend.

The RS 125 comes pre-wired for Bluetooth networking with your smartphone if you pony up for the optional infotainment package as well as an optional USB charger in the under-seat compartment that was enlarged for this year with room for an 8-inch tablet.

2021 Aprilia RS 125 Chassis

  • Aluminum frame
  • Big-bike handling qualities
  • Bosch 9.1 ML ABS – front only
  • Wider rear tire for stability and better grip
2021 Aprilia RS 125
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2021 Aprilia RS 125
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2021 Aprilia RS 125
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Aprilia pulls no punches with big-boy-bike equipment and a racebike design that is sure to delight new riders.

The RS 125 chassis enjoys a certain level of recognition as the only Italian-made ride in this displacement bracket to sport an aluminum frame with die-cast aluminum members and crossed reinforcement ribs to achieve its final structural rigidity. An asymmetrical swingarm finishes out the standing structure with fatter tires for this year for more substantial contact patches in a 100/80 ahead of a 130/70 on 17-inch rims at both ends.

A new, 41 mm inverted fork supports the front end on 4.3 inches of travel opposite a monoshock out back that boosts the travel up to 4.7 inches to fall in the usual range for a racing street bike. Here the GP variant diverges from the equipment on the base model with a set of 40 mm usd stems up front but the suspension stroke remains the same.

Aprilia again drew from its larger-displacement machines for the RS 125’s anchors. Metallic brake lines deliver undiminished pressure to the radial calipers that bite a 300 mm disc up front followed by a 218 mm with a four-piston anchor and single-pot caliper on the front and rear respectively. Bosch 9.1 ML ABS protection comes stock, but only on the front wheel, so the rear relies solely on rider skill.

Frame: Aluminum perimeter frame
Front suspension/ Travel: 40 mm upside down fork/ 4.3 in (110 mm)
Rear suspension/ Travel: Asymmetrical swingarm. Single shock/ 4.7 in (120 mm)
Brakes, Front: 300 mm stainless steel disc, 4-piston radial caliper
Brakes, Rear: 218 mm stainless steel disc, single 30 mm piston caliper
Wheels: light alloy with 6 split spokes.
ABS: BOSCH
Tire, Front: 100/80 - 17"
Tire, Rear: 140/70 - 17"

2021 Aprilia RS 125 Drivetrain

  • New liquid-cooled 124 cc single-cylinder engine
  • More power low in the rev range
  • More robust torque curve
  • Optional electronic quick-shift gearbox
2021 Aprilia RS 125
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2021 Aprilia RS 125
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2021 Aprilia RS 125
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A new single-cylinder plant powers the RS 125 with 14.75 horsepower on tap to make it qualify for A1 license use. Liquid-cooling eliminates the waste heat while dual over-head cams time the four-valve head for efficient aspiration and volumetric efficiency. The 58 mm bore and 47 mm stroke gives the mill a 124.2 cc displacement with a sizzlin’-hot 12.5-to-1 compression ratio that will demand top-hook fuels to prevent knock/ping/run-on, but that really shouldn’t be surprising given the RS family’s racing chops.

A throttle body manages the induction with electronic fuel injection to meter the hydrocarbons and help the engine meet its EURO-4 obligations, all under the control of the Magneti Marelli M3G engine control unit. A no-nonsense capacitor-discharge ignition system lights the fire and ensures proper flame-front propagation. Power flows through a standard wet clutch and six-speed transmixxer before heading to the rear wheel via an O-ring chain final drive, and the overall drive ratio turns out a top speed of 70 mph.

Engine: Four-stroke liquid-cooled single-cylinder with electronic injection and 4 valves, DOHC
Displacement: 124.2 cc
Bore x Stroke: 58 mm x 47 mm
Max Power: 14.7 hp (11 kW) @ 10,000 rpm
Maximum torque: 8.3 lb-ft (11.2 Nm) @ 8,000 rpm
Compression ratio: 12.0 ÷ 12.6 : 1
ECU: Magneti Marelli MIUG4 ø 32mm ECU
Ignition: Electronic with CDI capacity discharge
Starter: Electrical
Lubrication: Wet sump
Transmission: 6 speed
Gear Ratio: 1st 11/33 (0.33), 2nd 15/30 (0.50), 3rd 18/27 (0.67), 4th 20/24 (0.83), 5th 25/27 (0.92), 6th 23/22 (1.05)
Primary drive: Straight cut gears, drive ratio: 69/29
Final drive: Chain, drive ratio: 13/58
Clutch: Multiple discs, in oil bath

2021 Aprilia RS 125 Price

2021 Aprilia RS 125
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2021 Aprilia RS 125
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2021 Aprilia RS 125
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Price and trim level go hand in hand. The base-model RS 125 E4 rolls in a choice between Silver Speed and Black Speed for £4,499, and the GP Replica model with racing livery is a mere £ 100 more.

Color: Aprilia Black, Sintesi Blue, MotoGP Livery
Price: £4,499

2021 Aprilia RS 125 Competitors

2019 - 2021 Yamaha YZF-R125
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2021 Aprilia RS 125
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Yamaha has its own entry in the 125 cc race/street range with its YZF-R125 model.

Yamaha YZF-R125

2019 - 2021 Yamaha YZF-R125
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The Yammie carries updated digital instrumentation with new brake hoses and ABS features along with a proper MotoGP hand brake lever. It comes built around a twin-beam steel Deltabox frame in opposition to the aluminum favored by Aprilia, but ABS is a constant across the board and it looks like Yamaha applied it to both ends for a leg up over the Aprilia’s front wheel-only antilocks.

The 52 mm bore and 58.7 mm stroke describes an undersquare thumper in the YZF-R, but the real magic in this mill is in the top end. A solenoid controls the rocker arms so that below 7,400 rpm a low-speed cam provides lower valve lift and shorter duration, but above that speed the rocker arms are pinned together and operating off a high-speed cam for a relatively broad powerband.

As you’d expect from an A1 bike, the power output is limited to 15 ponies so power isn’t really a point of comparison here given those restrictions. Price is right on the nose at £4,499, so if you were expecting the sticker to settle the choice between these tow bikes, you’ll have to look elsewhere.

Read our review of the Yamaha YZF-R125.

He Said

“This is one of the top choices for would-be pegdragger larvae out there. Aprilia pulls no punches with big-boy-bike equipment and a racebike design that is sure to delight new riders. Plus, you can set it up for actual track use to make this a great platform for riders with podium aspirations. Too bad the newbies in the U.S. market won’t benefit from Aprilia’s vision as it seems that the company is content to not export it to our shores.”

She Said

My wife and fellow motorcycle writer, Allyn Hinton, says, “An improvement on the RS 125 this year is the increase in low-to-mid range torque, which adds a fun factor to it. It’s a snazzy little bike. It has a big-bike look in that RS sort of way. It’s what people want if they don’t want a scooter.”

2021 Aprilia RS 125 Specifications

Engine & Drivetrain:
Engine: Four-stroke liquid-cooled single-cylinder with electronic injection and 4 valves, DOHC
Displacement: 124.2 cc
Bore x Stroke: 58 mm x 47 mm
Max Power: 14.7 hp (11 kW) @ 10,000 rpm
Maximum torque: 8.3 lb-ft (11.2 Nm) @ 8,000 rpm
Compression ratio: 12.0 ÷ 12.6 : 1
ECU: Magneti Marelli MIUG4 ø 32mm ECU
Ignition: Electronic with CDI capacity discharge
Starter: Electrical
Lubrication: Wet sump
Transmission: 6 speed
Gear Ratio: 1st 11/33 (0.33), 2nd 15/30 (0.50), 3rd 18/27 (0.67), 4th 20/24 (0.83), 5th 25/27 (0.92), 6th 23/22 (1.05)
Primary drive: Straight cut gears, drive ratio: 69/29
Final drive: Chain, drive ratio: 13/58
Clutch: Multiple discs, in oil bath
Chassis:
Frame: Aluminum perimeter frame
Front suspension/ Travel: 40 mm upside down fork/ 4.3 in (110 mm)
Rear suspension/ Travel: Asymmetrical swingarm. Single shock/ 4.7 in (120 mm)
Brakes, Front: 300 mm stainless steel disc, 4-piston radial caliper
Brakes, Rear: 218 mm stainless steel disc, single 30 mm piston caliper
Wheels: light alloy with 6 split spokes.
ABS: BOSCH
Tire, Front: 100/80 - 17"
Tire, Rear: 140/70 - 17"
Dimensions & Capacities:
Max. length: 77.4 in (1,968 mm)
Max. width: 29.9 in (760 mm)
Wheelbase: 53.1 in (1,350 mm)
Max. height at top fairing: 44.7 in (1,135 mm)
Saddle height: 32.2 in (820 mm)
Curb Weight: 317.5 lb (144 Kg)
Fuel economy (WMTC cycle): 2.6 l/100 km
Fuel capacity: 3.8 gal (14.5 liters)
Details:
Color: Aprilia Black, Sintesi Blue, MotoGP Livery
Price: £4,499

Further Reading

Aprilia

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TJ Hinton
TJ Hinton
T.J got an early start from his father and other family members who owned and rode motorcycles, and by helping with various mechanical repairs throughout childhood. That planted a seed that grew into a well-rounded appreciation of all things mechanical, and eventually, into a formal education of same. Though primarily a Harley rider, he has an appreciation for all sorts of bikes and doesn't discriminate against any particular brand or region of origin. He currently holds an Associate's degree in applied mechanical science from his time at the M.M.I.  Read full bio
About the author

All images featured on this website are copyrighted to their respective rightful owners. No infringement is intended. Image Source: aprilia.com, yamaha-motor.com

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