Decathlon is entering business with its first mid-engine E-MTB, the Rockrider e-ST 900, following its first Rockrider e-ST 500 electric rear-assist mountain bike. A model that is intended for hiking, including in the hills.
Mountain biking, which is electrically assisted, is becoming more popular, but often quite costly.
At major brands, their prices often exceed the EUR 3,000 mark, which leaves space for specialists in the distribution of mass sports, including Decathlon.
Thus, with its mid-engined Rockrider e-ST 900 (twice the torque of the previous Rockrider e-ST 500; EUR 1,299), the French brand is hurrying into the niche of bicycles for less than EUR 2,000.
The e-ST 900 incorporates a 250 W Brose T motor with an impressive torque of 90 Nm (we will come back to it on paper anyway), coupled with a 504 Wh battery to take advantage of the performance and sufficient autonomy for mountain excursions.
Equipped with wide 27.5+ tires, suspended from the front by a Rockshox Judy fork and equipped with a Shimano Deore transmission, this semi-rigid is primarily aimed at the quality-performance/price ratio, as it is shown at EUR 1,999.
Because of the aggressive selling price of its equipment, E-MTBs of major brands appear for similar equipment at several hundred euros more (excluding promotions).
Comfort and ergonomics
With its large tires and especially its battery overcoming a good part of the diagonal tube, the Rockrider e-ST900 imposes some and cannot hide its electric character, despite a sober color made of gray, black and white.
The Brose motor is also clearly visible, positioned in its protective casing along the same axis as the battery.
The integration of these components gives pride of place to plastic and the finishes unfortunately leave a little to be desired.
One ticks in particular on the rubber of the junction between the engine crankcase and the seat tube, which ensures only a rather summary seal.
In general, dirt can seep into the crankcase too easily, making cleaning more delicate.
We will probably not escape a little in-depth cleaning from time to time, but it will then be necessary to disassemble a few parts …
Nothing abnormal however at this level of the range, we did not expect a total integration of the battery nor a perfect integration of the engine into the frame.
This is precisely what distinguishes a € 2,000 E-MTB from other models that are 50% or even 100% more expensive.
In terms of integration, therefore, we must not be choosy, but the engineers at Decathlon have nevertheless managed to keep a frame geometry fairly close to that of classic mountain bikes (called “muscle”).
Apart from the curved shape of the seatstays and the top tube – which, however, gives the bike a little more character – we are therefore faced with a frame of reasonable dimensions.
The chainstays remain quite short (449 mm) thanks to the orientation of the motor upwards, thus limiting the wheelbase of the bike to keep good handling, while the depth of the frame ( reach) varies quite clearly between size S and XL (from 379 mm to 445 mm) to suit all sizes.
The riding position nevertheless remains straight enough for a mountain bike and it is even possible to adjust the angle of the stem to raise the handlebar (5 steps of 7.5 mm, from 0 to 30 mm) and thus adopt the position of piloting that we prefer (more or less lying down).
In terms of comfort, we appreciate the wide 2.8 “Taipan Koloss 27.5+ tires which provide good shock absorption and somewhat compensate for the absence of a rear shock absorber.
The bike is rather heavy (22.1 kg in size M) and its fairly rigid 6061 aluminum frame, the choice of wide tires seems relevant to us, especially as an E-MTB needs good grip to ensure traction.
Note that if these are mounted on 36 mm tubeless compatible aluminum rims (Sunringle Duroc 40) .
The B’Twin Ergofit Evo saddle, for its part, provides enough cushioning for a mountain bike thanks to a good thickness of foam.
We can always opt for a suspended seat post for more comfort, the diameter of 31.6 mm of the original post being standard, but we would rather recommend a telescopic seat post if we often alternate between climbs and descents. .
On the front wheel side, however, we can count on the Rockshox Judy hydraulic fork to withstand the impacts.
With its 120mm travel, rebound adjustment and triple clamp, this entry-level fork is well suited to a not too committed XC or trail practice.
Although it is a mountain bike, Decathlon supplies lights, bell and wheel reflectors with its e-ST 900, in order to comply with the legislation on the sale of bicycles.
Entry-level plastic flat pedals are also delivered, but they will soon be replaced by other better quality pedals.
As regards the control of the engine, there is a small all-in-one on-board computer attached to the side of the left handle.
This lights up simply by pressing and holding the top button. Navigation in the menus is done without difficulty with a small clickable joystick with 4 directions.
The home screen shows the instantaneous speed and, in the form of sticks, shows the selected assistance mode and the remaining autonomy.
You must scroll through the screens using the joystick to obtain an estimate of the range in kilometers, the distance travelled or the power exerted on the pedals (in watts).
Too bad that at the same time as the instantaneous speed and, above all, the chosen level of assistance, this information can not finally be displayed!
To know which mode is activated, it is indeed necessary to remain on the main menu, which is hardly practical.
A small bonus, for example, is a micro-USB socket available on the right side to power a smartphone or a GPS.
The Brose T mid-engine, the key element of this Decathlon E-MTB, relies on its impressive torque of 90 Nm (when most competing engines peak at 75 or 80 Nm).
A torque that we find surprising, as the Brose T shows a torque of 70 Nm with its maximum support at 320 percent on the official Brose website.
This is not necessarily a Decathlon error, Brose was able to provide a customized version of his engine very well having it. We are awaiting Decathlon clarification at the moment.
Nevertheless, raw power is not everything, particularly since engine manufacturers are not bound by standards and thus indicate the values that best suit them.
In this case, a pinion gear or, in the case of this Brose T motor, a belt can decrease the torque at the output of the motor.
It is impossible to know the actual power transmitted to the wheel based on the manufacturers’ technical data.
This is why we assess in practice the behavior of the motor and the approval of electrical assistance.
There’s nothing like testing for that in the forest with elevation drops, but you still need to get there.
So it was the first time we had the opportunity on the road to check how the Rockrider e-ST 900 was doing.
“And it was a good surprise, since we have noticed that the bike is very rolling, a sign that the friction linked to the engine is limited and that the chassis “holds the road,” even with the engine off and despite the 2.8 “tires.
We appreciate the engine’s smoothness as well as its silence.
It does not take long to activate the electrical assistance, because if driving on the flat is done at a good pace, we are quickly remembered by the 24 kg of our test model in size L on the first climb.
The first assistance mode at + 40 percent then allows this overweight to be compensated.
But it is indeed on degraded roads that a VTTAE is evaluated, and mode 1 is no longer sufficient in this case.
By pressing the arrow keys to the left of the on-board computer, the assistance mode is altered.
We would have appreciated them a little wider and especially flatter, since the angle they form in relation to the handle requires them to be pressed to the right with the tip of the thumb, an operation less natural than pressing down or at least perpendicular to the handlebar axis, as
We, therefore, call the second economy mode quickly, providing + 80 percent assistance.
If it is enough to hike quietly most of the time, it shows its limits as soon as the slopes become steeper.
It is then actually mode 3 (called “Standard”) that we do not hesitate to participate at + 160 percent to benefit from assistance.
You end up using this mode most of the time, as it is the one that offers t
In order to reduce the risk of derailment, E-MTBs favor the single chainring.
The e-ST 900 also benefits from a chain guide and its chainring benefits from ChainFlow technology, which should in principle ensure that it never derails.
Despite these safeguards and the use of a reinforced chain, while crushing the pedals, we will still avoid changing gears too wildly to respect the mechanics.
Nevertheless, the Shimano Deore M6000 Shadow + derailleur allows for rapid gear changes.
We appreciate that on this point, Decathlon did not seek too much economics and is not satisfied with an Altus derailleur.
It must be said that the Rockrider e-ST 900 is more intended for high mountain rides, dixitDecathlon, a fairly demanding mechanics playground.
This is also why this model has a fourth mode (‘Boost’), bringing the assistance to + 320 percent this time. Enough to climb mountains, the engine running at full speed and talking about its torque of 90 Nm.
Our emergency braking test on the flat results in a stop in less than 3 m, aided by the large tires, no doubt.
The range varies totally with a VTTAE, even more than with an urban or even all-road electric-assisted bicycle.
Of course, the difference in height, but also the state of the ground (muddy, dry…), the tire pressure, not to mention the driving mode, the pedaling frequency and…
The Mountain Biker’s Weight. (about 85 kg, fully equipped and with a water reserve, in our case).
” 3 hours on average in sports mountain biking use”average 3 hours of sports mountain biking use.
We drove a loop of almost 6 km in the forest in Standard Mode until the battery was empty.
We took care to maintain a pedaling rate above 60 rpm while avoiding exceeding 25 km / h, since in order to comply with the law defining an eBike, electrical assistance is automatically cut off above this speed.
Result: in just under 2 h, almost 44 km swallowed.
A distance that can therefore increase quite significantly if we’re careful to pedal in economic mode when the use of the standard mode is not necessary and the ground is flat (our other more ‘utilitarian’ riding periods with this bike went in this direction, despite an estimate of autonomy that did not want to go down on the meter…), or decrease until falling at a small thirty kilometers
Allow about 3 hours to refuel, as for recharging, which is quite reasonable for a 14 Ah 36 V battery.
This is done directly through a battery connector, which is accessible even when she gets on the bike.
However, with a simple turn of the key, you can remove it by pushing it to the left of the bike if you want to take it with you (and take away a good part of the value of the bike).
In practical terms, on the top of the battery, there is a charge level indicator with 5 LEDs. In passing, it should be noted that Decathlon guarantees its battery for 2 years or 500 cycles of charge / discharge.
A Samsung SDI cell battery that, according to Decathlon, at the end of the warranty, must also hold about 70 percent.
The Rockrider e-ST 900 is a mountain bike with balanced electric assistance that benefits from uniform equipment.
We’re not going to go so far as to recommend its handlebars a dedicated practice, but it nevertheless turns out to be a good hiking companion, whether it’s taking advantage of its motorization to ride further and higher, or just being able to follow a group of sharper mountain bikers.
In any event, its central Brose engine provides sufficient power and enjoyment to take full advantage of the benefits of electrical assistance, whatever the motivation for switching to a motorized bike.