Rieju 125 SM Pro – 2021 (Weektest)

The Rieju 125 SM Pro is the 125cc Supermotard from the Spanish brand. While Rieju is primarily known for their 50cc scooters by many people, they also offer some 125cc and 300cc motorcycles. The 300cc models are not street-legal and are purely for enduro or off-road use. For the 125cc models, Rieju uses the liquid-cooled engine blocks from Minarelli (Yamaha). These Yamaha engines are known as one of the best 4-stroke 125cc engines in the world, which is a positive start for Rieju’s models. In addition to the Rieju Marathon, Rieju also offers naked and touring models in the 125cc category.

The Rieju 125 Pro vs SM Pro

The Marathon is offered in 2 versions: the 125cc Pro and the 125cc SM Pro. Both share the same engine and frame, yet they differ from each other. The biggest difference lies in the wheels, which are immediately noticeable. The Pro comes with spoked wheels and off-road tires, while the SM Pro comes with alloy wheels fitted with road tires. To make the SM more road-oriented, the wheel sizes vary as well. The Pro features 80/90-21 front and 110/80-18 rear wheels, whereas the SM Pro comes with 100/80-17 front and 130/70-17 rear wheels. However, the wheels are interchangeable and easy to swap as needed.

Another advantage, in the newer models, is that the SM Pro features a rear shock absorber with an external reservoir. Due to the smaller wheels on the SM Pro, the seat height is automatically slightly lower, at a comfortable 870mm. For a 125cc motorcycle, this still offers a relatively high seat. In terms of weight, both models are delivered dry at 121 kg, with a 6.3L fuel tank. Both models come with an aluminum handlebar.

A mature looking Supermoto​

One striking feature of the SM Pro is its height. I had to place it next to my XT660R, and surprisingly, the height difference is quite small. The advantage of its height, combined with the upside-down front fork and the raised front fender, is that the SM Pro looks like a “mature” motorcycle. The space created by this offers ample suspension travel, so you don’t have to worry about your front wheel hitting the fender, regardless of your riding style. Compared to the XT, the Rieju has an angular front fender that complements the rest of the plastics. The white color scheme, angular headlight, and sharp lines on the side panels contribute to a sleek and stylish design. The frame runs smoothly through this, and everything seems to be designed to match. The round turn signals stand out from the design, but most will replace them with small, inconspicuous LED signals. The handguards follow the sleek lines and are more about looks than functionality; an inspection inside the guards reveals a sticker warning that they do not offer real protection upon contact. Therefore, if you plan to ride more off-road with the SM Pro, it is advisable to replace the handguards.

The 125cc engine hangs fully visible in the black frame, with only a small part of it tucked away behind the side panel at the top. On the right side, the exhaust comes out from behind the side panel, with a small heat shield to protect your new Kevlar jeans. The standard exhaust muffler is located to the right of the center, allowing ample space for the rear wheel to move. While riding, you can clearly hear the standard exhaust, but it is not excessively loud, which is nice for commuting. Once again, there are round turn signals at the rear. A highlight at the back is how the rear/brake light is integrated. Neatly tucked under the rear fender, it blends in seamlessly with the overall design of the SM Pro. The rear fender sits fairly horizontally and fits snugly against the seat. This narrow but long seat seamlessly integrates with the design of the sticker panels, making the Rieju a cohesive unit from front to back. This makes the SM Pro a real head-turner, with its SM look, height, and single-cylinder sound catching the attention of many passersby.

The Minarelli engine

The Rieju 125cc comes with the four-stroke, single-cylinder Minarelli engine. This liquid-cooled engine has been used by Yamaha for several years, which has the advantage of readily available parts. Not only spare parts but also aftermarket optional upgrades. The standard engine delivers 11 kW of power at 9,000 rpm and 11.5 Nm of torque at 8,000 rpm. The SM Pro does not feature fuel injection but still uses a genuine carburetor, a Keihin 39s. This has disadvantages but also benefits, as it offers opportunities for fine-tuning for those who want to customize the SM to their liking. The SM Pro also comes with a choke for colder days, variable idle speed, and a fuel tap with reserve. Something you don’t see very often nowadays.

All this, combined with its smooth throttle response and lightweight design, 121 kilograms ready to ride, results in agile handling and makes it a delightful “throw-and-go” bike. Accelerating up to 90 to 100 km/h is smooth, and getting onto the highway is therefore no problem at all. Overtaking and/or accelerating above 100 km/h is a bit more challenging, as you reach the limits of the 125cc engine. On paper, a top speed of just over 120 km/h means that the Rieju comes close to Yamaha’s WR125X, but not quite. The smaller fuel tank means you’ll need to refuel every 140 to 150 km, but you only need to fill up 4.5L, so it’s not a big deal. The tank capacity itself is 6.3L, but part of that is the reserve. It’s convenient in case you haven’t planned a gas station within that 150 km range. The downside of the tank is the non-lockable fuel cap, so anyone could unscrew it. Aftermarket options are already available.

Exploring Grip, Suspension, and Braking Dynamics

The SM Pro comes with alloy wheels fitted with street tires. As standard, the SM Pro is equipped with 100/80-17 front and 130/70-17 rear Mitas MC-25 Bogart tires. Although there are better tires available on the market, the MC-25’s proved to be reliable tires. They offer sufficient grip on the asphalt, particularly in corners. Even in wet conditions, the grip was adequate to come to a stop with a stoppie at a traffic light. Off-road, they naturally leave something to be desired, but for true off-road riding, you need proper off-road tires. However, navigating through grass or even riding on the dike posed no problem. The non-adjustable Marzocchi upside-down front fork, with a 40mm diameter, is sufficient for most SM Pro riders. For more aggressive riding styles (wheelies, visits to skateparks, jumping), you may want a bit more damping. This can be achieved by using different fork oil or installing an aftermarket set. However, for normal everyday use, the Marzocchi upside-down fork is more than suitable for the lightweight SM Pro.

Both front and rear of the Marathon SM Pro have a single disc brake. At the front, there’s a 300mm disc with a dual-piston caliper, while the rear features a single-piston caliper with a 200mm disc. Since 2016, a combined braking system (CBS) is mandatory for 125cc motorcycles, which can be used instead of ABS. The Marathon 125 SM Pro is equipped with this CBS system. This means that both brakes are always engaged, even if you consciously use only one of them. However, with CBS, there’s a ratio that’s not 50/50. This allows you to deliberately lock the rear wheel with a firm press on the rear brake. The front brake, with CBS, is powerful and precise enough to lift the rear wheel off the ground on demand, with enough play to keep rolling, all while maintaining a sense of complete control.


Riding the Rieju Marathon 125 SM Pro offers a rather unique experience, despite the increasing popularity of supermotards and dual-sports. The SM Pro boasts a sleek appearance, high-quality finish, and smooth, enjoyable ride. The Minarelli 125cc engine provides reliability and the advantage of being used by Yamaha, with many aftermarket parts available. All this comes at a more affordable price than a Yamaha. While the SM Pro may not be the fastest 125cc on the market, it compensates with fuel efficiency and lightweight design. Its playful nature makes it a highly suitable motorcycle for urban riding, appealing to both novice riders and experienced riders looking for a small bike.

However, there were two minor issues that disappointed me during the week I had the SM Pro. The first issue may seem trivial, but it was something that bothered me. The position of the starter button is so far inward on the handlebar that you can’t reach it from the grip. Every time you start it, you have to let go of the handlebar. It’s an unnecessary action, but perhaps it’s a matter of getting used to it or seeing if it can be relocated with some tools. The second issue was the seat. While the narrow, long seat offers sufficient grip and seating space, it’s actually not adequate for long rides of 3 hours or more. It’s difficult to say whether this is due to the narrow profile of the seat or the density of the padding. However, this is something that can be improved upon if it bothers you. Despite these two drawbacks, the Rieju Marathon 125 SM Pro offers a lot of positives for its price. It’s a 125cc motorcycle that compares favorably with the often more expensive competition. It comes across as reliable and robust, with plenty of room for real fun. The SM Pro is available in two colors (black and white) and comes with a 2-year warranty.


Single cylinder, four stroke

Cylinder capacity


Bore x Stroke

52.0 x 58.6 mm


Carburetor (Keihin 39S)

Max power

15HP / 11kW @ 9.000 rpm

Max torque

11,5 Nm @ 8.000 rpm


6 speed



Strong double cradle steel perimeter. Removable rear subframe

Front suspension

Upside-down front fork, 40mm

Rear suspension

Mono-shock shock absorber

Front brakes

300mm single disc with double piston caliper

Rear brake

200mm brake disc with single piston caliper


Alloy wheels

Front tire


Rear tire



2070 mm (81.5 inches)


800 mm (31.5 inches)


1145 mm (45.1 inches)


1380 mm (54.3 inches)

Seat height

870 mm (34.3 inches)

Ground clearance


121 kg curb weight

Fuel capacity

6.3 Liters (1.66 US Galllons)

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