2005–2006 · Supermoto · Buyer's Guide
Two-Stroke Supermoto Pocket Rocket
The MX 125 Supermoto is a real supermoto built down to 125 cc, not a commuter dressed up as one. At its heart sits a liquid-cooled two-stroke single from the Rotax family that Aprilia also uses in the RS125 sportbike. It's rated at 15 hp and runs through a 6-speed box and a chain. The hardware around it is full-size: an upside-down fork with 10.2 in (260 mm) of travel, 11.0 in (280 mm) at the rear, a 12.6 in (320 mm) front disc and 17-inch rubber at both ends. On paper, this is Aprilia taking the small class seriously. No toy here!
Read the numbers and the intent is clear. A 35.0 in (890 mm) seat, 11.4 in (290 mm) of ground clearance and long-travel suspension put it in the tall, narrow supermoto mold. It's built for tight back roads, city traffic and short, technical blasts, not long highway stints. The 2.9 gal tank and 29 mpg keep your radius short. The rear shock takes preload adjustment, but the fork doesn't adjust. The engine is top-end biased and a two-stroke wants regular maintenance, so the hardware points to a rider who keeps it on the boil and keeps up with the wrenching. It's a skills machine. Not a sofa.
Spec sheets don't ride bikes, but they set the baseline.
| Power | 15 hp (11 kW) |
|---|---|
| Displacement | 125 cc |
| Engine | Single-cylinder |
| Cooling | Liquid-cooled |
| Gearbox | 6-speed |
| Final drive | Chain |
| Fork | Upside-down (USD) |
| Front brake | 320 mm |
| Front tire | 110/70-17 |
| Rear tire | 150/60-17 |
| Ground clearance | 11.4 in (290 mm) |
| Front travel | 10.2 in (260 mm) |
| Rear travel | 11.0 in (280 mm) |
| Seat height | 35.0 in (890 mm) |
| Fuel capacity | 2.9 gal (11 L) |
| Fuel economy | 29 mpg (US) |
Equipment check
Chassis
I've spent years listening to the people who own these bikes: in the paddock, at club nights, and in the emails and messages that land in my inbox. For the MX 125 the chatter splits cleanly in two. Riders rave about how it rides and stops, and they grumble about what it takes to keep one alive.
The front brake comes up again and again. Owners describe strong, progressive stopping power with real feel, and they rate it above most other bikes in the class. The suspension gets the same respect: riders like that they can set the rear shock's preload for the road or an occasional track day. The fork doesn't adjust. And the engine's top-end rush is what they call addictive. That's the hook.
The recurring complaint is upkeep. Owners talk about regular top-end rebuilds, and they warn that neglect ends in expensive damage. Switchgear failures get mentioned just as often. Less frequent, but still a pattern: young riders find it expensive to buy and insure next to tamer alternatives, and some owners call the six-speed gearbox notchy, with false neutrals when you rush a shift. It wants deliberate shifts.
Electrical connector corrosion
Wiring loom connectors, particularly those exposed to road spray, are prone to corrosion, causing intermittent failures of lights, indicators, and the digital display.
Speedometer inaccuracy
The speedometer is known to over-read significantly, which can lead to misjudged speeds and potential legal issues.
Exhaust system corrosion
The stock expansion chamber and silencer are painted in a cheap matte black coating that rapidly rusts, especially when exposed to wet weather.
Where this Aprilia MX 125 Supermoto pulls ahead of — or falls behind — its rivals on the numbers, and the typical bike in its class on character.
Power
Displacement
Seat height
Forget spec-sheet bragging. Here's who the MX 125 Supermoto is actually built for.
Of these riders, you're the best fit: the chassis is built for lean and quick direction changes. Just know that 15 hp makes it a tool for tight canyon sections, not long fast sweepers.
Made for Angeles Crest Highway · Coronado Trail / US 191 · Highway 1 / Big Sur
A good match if skill beats speed for you: light handling and generous lean clearance suit tight, repeated curves. The highway miles to get there on a 2.9 gal tank are the weaker part.
Made for Tail of the Dragon · Back of the Dragon · Blue Ridge Parkway
If this one isn't quite the fit, these are the bikes worth riding back-to-back against it.
