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Rockrider e st 900 : High end electric mountain bike test

The best electric mountain bikes of the moment

Decathlon is one of the leaders in the sale of affordable electric bikes. In order to guide you to make the right choice, we have made a selection of the best references.

Buying an electric mountain bike is not for everyone. An electric bike can reach very high prices if you are looking for quality. But there are some that offer quality at a decent price: the Decathlon Rockrider e st 900 is one of them. It’s fun to ride, well equipped and unbeatable value for money.

Discover the electric Rockrider range from Decathlon

Decathlon is very present in the electric bike sector and offers a wide range of electric mountain bikes. The electric Rockrider is a mountain bike of great quality of manufacture and composition accessible to the general public.

It is available in 4 different versions to satisfy all budgets. The electric Rockrider, whatever it is, has an exceptional manufacturing quality and a very elegant finish and design.

Built around a solid 6061 aluminum frame, the electric Rockrider st 900 looks like a real racer. It’s equipped with a Rock Shox Judy fork with 120mm of travel up front, Boost-spec wheels, 2.8-inch large-camber tires and a 10-speed Shimano Deore transmission.

The bike also features a proper mid-motor courtesy of Brose, and a 500Wh battery for a full day of exploring…

Distinction of the ranges

In the past, Decathlon mountain bikes were already signed Rockrider under the B’twin range. Decathlon then decided to simplify all this by renaming all its bike ranges.

Thus the mountain bikes became as we said the “Rockrider” range, the mountain bikes “Riverside”, the urban bikes “Elops” and the racing bikes “Titans”. You can of course find the reviews of these different ranges on our platform.

It was therefore very obvious for Decathlon to expand its product catalog. After the big success of the Rockrider 520 it was time to create and propose its new electric bikes.

Introducing the Rockrider e st 900

I would describe the geometry of the Rockrider e st 900 as fairly traditional in terms of a mountain bike. But really, it’s not a bike for demanding, pro-style big riders: it’s a bike for riders like me, who are reasonably competent off-roaders but not gravity hunters.

I spend most of my off-road time on local trails and bridle paths, which aren’t very technical and require tarmac runs to connect them; and this Rockrider st 900 is just right for that kind of riding. There are faster, more capable bikes for off-roading, to be sure, but the 120mm Rock Shox Judy fork can take some pretty big hits.

The Rockrider e st 900 is also stable enough to be used in fairly technical situations. It’s quite capable of handling blue trails in a bike park, or red ones if you’re a little careful. I for one don’t like to go any further anyway!

Technical specifications of the Rockrider e st 900

Let’s take a look at the technical characteristics of this electric mountain bike in order to remember the important points that mark the Rockrider st 900.

The operation

About the Brose motor. It is a Decathlon specific construction that, according to the company, has a power of 90 Nm. Like all Brose motors, it is very quiet and the way it applies the assistance to the rear wheel seems very natural.

Control is from a handlebar-mounted remote that offers four levels of assistance: 40%, 80%, 160% and 320%. This percentage is the multiplication of the effort you will put in to move the Rockrider 900 forward.

An LCD screen shows you your speed and all other parameters, as well as a human power reading indicating the level of effort you are providing.

The remote isn’t the easiest to use that I’ve tried – the buttons are flat on the surface of the device and not always easy to spot with gloves on – but it’s decent enough.

The battery life reading is indicated by four bars. The battery consumption is linear, the last bar representing the end of the battery offers a similar autonomy to the first. This means that the battery does not work in degraded mode at any time.

3 modes of operation are then possible via the LCD screen installed on the handlebars. You will be able to define the level of difficulty or rather the level of electrical assistance that the electric mountain bike should provide. These 3 modes are the following :

  • Economic : To save the battery, in this case it is up to you to make the most physical effort to move the mountain bike
  • Standard : Where the electric mountain bike takes part in your journey by providing its “normal” assistance
  • Boost : Finally via this mode, the bike will do more than you. After a few hours of mountain biking you will understand the interest of this mode. Quickly return at home to take a good shower.

Performance and motor skills

In terms of absolute power, the motor is not as punchy as some. It doesn’t seem to be able to compete with a Bosch Performance Line CX or Shimano STEPS E8000 motor, but it’s still very close and still exceptional considering its price.

To get a comparable motor – a Performance Line or E7000 – from most other brands, you’ll have to pay around 2300 euros, or much more in many cases.

The Rockrider e st 900’s engine allowed me to easily access any steep trail I encountered. There were times when my technical abilities were challenged on steeper, more technical slopes, but the engine was always up to the task. And the bike got me to the top.

It’s never a free ride: it took a bit of physical effort, as the bike weighs about 22 kg, but that wasn’t a problem thanks to the electric motor assistance.


Riding range is very rough on an electric mountain bike, but with a motor that offers a wide range of assistance levels and a 500Wh battery, you should be able to go on a good long ride with the Rockrider.

I was able to easily complete a 25km, 1.5 hour ride, which was a mix of road and trail, and ended up only using half the battery.

The terrain was quite hilly on my route, and with about 500 meters of elevation change. I was not particularly economical in the choice of the mode. Once the battery is discharged, it’s easy to plug it in and recharge it, although it’s not a quick operation.

This is not a bike that can be meaningfully recharged for more than an hour break at lunch, you really need to plug it in overnight to be sure you have full range for the next ride.

Weight and size

Concerning the weight of this electric bike, it is 22kg and the maximum load it can support is 120kg (mountain bike + user + accessories and equipment). The weight of this electric bike is still decent compared to its competition.

This travel companion comes in several sizes to fit your size: from size S (1.50m to 1.64m) to size XL (1.85m to 2.00m).

Equipment of the Rockrider e st 900

Several accessories are also delivered with this partner of excursion: a bell, reflectors of wheels (reflectors) and pedals.

No lighting is included with this electric bike, it is above all a mountain bike. But if you think that you are missing some accessories, you can add others like mudguards, a kickstand or a water bottle holder.

Comfort and safety

The safety options offered by this electric Rockrider 900 electric are not negligible. Wider and stronger rims and wheels to adapt to your playgrounds, ensuring you a strong and secure fit.

This Decathlon bike is also equipped with dual 180mm hydraulic disc brakes. This allows a quality braking, powerful and progressive. It has flat pedals with a wider support surface. They are also adorned with small spikes on the entire surface to avoid any risk of slipping when the feet are supported.

The price

The electric Rockrider 900 is one of the highest quality electric bikes Decathlon offers. Its price of 2099€ remains of good invoice considering the very good characteristics proposed by the mark. Many electric bikes are sold nowadays well above 2000€.

However, Decathlon has managed to impose itself with an attractive and competitive price, which will tickle the sometimes high prices of the competing brands present on the market of the electric mountain bike.

Rockrider e st 900 : Warranty

The warranty remains an important point in the choice of a Rockrider st 900 and here Decathlon proposes a lifetime warranty for the frame, the stem and the handlebars. As well as an availability of spare parts during 2 years. Concerning the battery, the latter is guaranteed 500 cycles by the giant of the sector.

In sum

Was there anything that wasn’t up to par on this Rockrider e st 900 ? Well I will say that Decathlon’s choice in tubeless tires is a good choice – the 36mm Sun Ringle rims are excellent – but the Hutchinson Taipan tires, in my opinion, didn’t really do the trick.

They have a shallow tread and a fairly hard compound. They provide good handling on the tarmac, but are pretty scatterbrained in the corners. Off-road, in the mud, they didn’t really do the trick and lacked bite. It’s hard to find a suitable bike tire for all conditions. This would be my bike, I would definitely be tempted to replace them with a higher range.

Bought in February 2021, incredible bike I enjoy with

After 2 rides, I am very satisfied with the bike, a lot of response. Very satisfied with my purchase for the moment.

Competition from Rockrider e st 900

The Rockrider e st 900 is a very good product but it faces a tough competition and that’s why we propose you to discover the selection of our team. This selection takes into account the quality of manufacture, the equipment but also the price of the Rockrider 900.

The prices vary easily from simple to double in the world of the electric bike, first in cause of the quality of product. That’s why we wanted to select, in our opinion, the best electric bikes on the market. These electric bikes, ranked in the top 3, are among the toughest competition of the Rockrider e st 900.

Interesting purchase aids

These state subsidies, which can be combined with those of the local authorities, are extremely interesting in view of the initial price of the Rockrider st 900. They can in most cases allow a significant reduction of the purchase price.

Please note that these aids (purchase bonuses) are limited in time, it is important not to lose time to take advantage of them. To find out if you can benefit from this aid, we advise you to contact your local authorities.

Rockrider e st 900 Technical Sheet

Let’s go over the technical points of the Rockrider e st 900 that will make it an excellent partner for amateur adventurers.

  • 27.5 inch mountain electric bike
  • Available in several sizes: S – M – L – XL
  • Electric assistance allowing a tenfold increase up to 320%.
  • Pedestrian mode to compensate the weight of the bike
  • 6061 aluminum frame with hydroformed tubes
  • ROCKSHOX JUDY 120mm hydraulic fork suspension
  • Wide tires
  • Central motor BROSE 70Nm 250W
  • 500Wh 36V 14Ah battery (average autonomy of 3h in sport mode)
  • Control screen on the handlebar (LCD)
  • 4 operating modes: Eco+, Economy, Standard and Boost
  • SHIMANO DEORE transmission
  • Oversized 180mm hydraulic disc brakes Tektro TKD32
  • Weight 22kg and a maximum load of 120kg
  • Designed in France

To conclude

The tires are a relatively minor issue, which is easy to remedy if you end up feeling the same, so let’s not lose sight of the big picture: for about 2000 euros you get a Brose motor, 500Wh battery, tubeless Boost wheels, Shimano Deore drivetrain, Rock Shox fork and a handy finishing kit.

The Rockrider e st 900 is amazing value for money. There is literally no other electric mountain bike I can think of that can match it so closely. Add to that the fact that it is fun to ride and performs well enough on fairly technical terrain.

If you like to get out and about off-road and are content with a more traditional geometry, you really need look no further than the Rockrider 900.

To help you in your choice, our OnMyBike team offers daily articles on electric and traditional bikes.