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ROCKRIDER E-ST 900 Women's Electric Mountain Bike - 27.5+

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until £1,699.99 -%


This price includes a recycling fee for electrical equipment and batteries DecathlonDeeeTaxMentionAfterPrice / Since

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£1,699.99 -%
This price includes a recycling fee for electrical equipment and batteries DecathlonDeeeTaxMentionAfterPrice / Since

* From To

* Sales from to Until end of stock
* From and limited stock
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Our most powerful Electric Mountain Bike to date. This Rockrider pedelec hardtail MTB will allow you to climb faster and rider further than before. A true off road e-bike built for comfort and control thanks to the relaxed geometry, wider bars, 120mm travel Rockshox Judy forks, Shimano Deore M6000 groupset, 40mm rims, front & rear thru axles and wide 27.5x2.8 tyres. Powered by the reliable BROSE T 90 Nm central motor with a Samsung SDI cell battery (504Wh 36V 14Ah) and built around the Lifetime warranty hydroformed alloy Rockrider frame, this e-MTB really is built to last.
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We currently have limited capacity to build bikes in our warehouse. Due to this, we are limiting the number of bikes we sell per day. If you are unable to process your order at checkout, please return the following day to make your purchase.


Product benefits

Anatomic design Comfort for women: saddle, adjustable fork, raised position, closer brakes
Power Overcome any slope with its motor with 70 Nm torque.
Autonomy Average ride: 4 hours, or 58km, of sports MTB use - 504Wh 36V 14Ah.
Smooth pedalling Pedal naturally with its built-in central motor. Essential for mountain biking

Technical Information


You have to pedal to go forward!
Electric assistance gives you up to 320% more pedalling power to get through obstacles, enjoy your mountain bike rides for longer, and help slower riders keep up in a group.
The motor stops when you stop pedalling.
The pedestrian mode offsets the mountain bike's weight when you need to stop.


Several sizes available:
S: between 1.50m and 1.64m
M: between 1.65m and 1.74m
L: between 1.75m and 1.84m
If you are on the limit between 2 sizes:
Choose the smaller size for easier steering (easier to handle).
Choose the larger size for easier pedalling and comfort (straighter back).

A word from the team

Our team of mountain bike enthusiasts created this E-ST 900 electric mountain bike at our B'Twin Village in Lille, France. We designed and tested the E-ST 900 MTB by involving MTB riders at every stage of the project.

A frame combining durability and pleasure to ride

The frame of the Rockrider E-ST900 has been made from 6061 aluminium with hydroformed tubes. Why?
The battery and motor sit snugly on the frame to improve the robustness of this electric mountain bike.
The forged aluminium parts enable it to be compatible with the new 27.5+ tyre format (wider than the 27.5") whilst still being easy to handle.

A motor with 90Nm torque to climb any slope

The BROSE T Aluminium central motor is specially designed for high altitude mountain biking:
- 70 Nm torque to handle any slope
- metal housing for maximum durability
- belt for an ultra-quiet motor
- and watertight bearings to withstand environmental conditions, which can be tough when mountain biking.


Our battery is equipped with SAMSUNG SDI cells, renowned for their high level of reliability and safety.
Our battery supplier sources its minerals responsibly and sustainably, and is part of the "Responsible Minerals Initiative".

A battery that's easy to lock

Our Rockrider mountain bike team has designed a battery that locks in place with a simple lever.Child's play!This locking system prevents any vibrations to the battery when you go adventuring on rough terrain. A key lock is also installed to help protect your battery from theft, For example, if you park your bike in the street.

A simple, ergonomic control screen

A discreet LCD control screen. Located just to the side of your left handlebar, choose between the 4 assistance modes without letting go of the grip: Deactivated, Economy, Standard, and Boost.
You'll also find a host of useful information:
Assistance level
Battery level
Speed (instant, average, maximum)
Power supplied by the user
Remaining battery life
Distance covered (total and trip)
Micro USB plug for charging your smartphone/GPS/camera...

4 assistance modes for any situation

Mode 0 - Deactivated
The battery is not used.
Mode 1 - Economy +40%:
Extend your rides while conserving battery life. Ideal when you want a little push on small gradients.
Mode 2 - Economy +80%:
Gain power. A perfect helping hand for keeping up with other mountain bikers.
Mode 3 - Standard +160%:
This is the most versatile mode. Climb any incline without tiring yourself out and avoiding using too much battery.
Mode 4 - Boost +320%


The E-ST900 electric bike is equipped with a single chainring and ChainFlow 3D anti-drop technology to prevent chain drops. An end to confusion:simply change between the 10 speeds using the single shifter on the right handlebar.
In detail:
- ChainFlow & anti-slip 34-tooth chainring
- Shimano Deore M6000 Shadow+ rear derailleur
- Shimano Deore M6000 shifter
- KMC e10 Turbo electric specific chain
- 11 - 40 Shimano Deore 10 speed cassette

27.5+ Sunringle Duroc 40 Wheels

These wheels were specially designed for this mountain bike:
- 36mm rims for improved durability and good grip on 2.8" wide tyres.
- BOOST format thru axles (12x148 rear, 15x110 front) for greater durability
- Aluminium hubs with sealed bearings.
- Tubeless ready compatible


So you feel safe on any terrain and for traction adapted to your motor, the E-ST900 mountain bike is equipped with Hutchinson Taipan Koloss 27.5+ tyres, 2.8" across. Our test riders particularly liked these tyres for their grip on the ground. Mounted on wide rims, these tyres ensure grip, traction, and comfort. On any terrain.


No matter the conditions you ride in (dry, muddy, wet), the Tektro TKD32 hydraulic disc brakes on the front and rear provide powerful, progressive braking. Oversized 180mm diameter discs provide even more power.


With its adjustable stem, the E-ST900 controls are close at hand. The all-aluminium B'Twin stem is 60 mm (size S/M/L) and can be raised using 5 adjustment intervals: + 0mm, + 7.5mm, + 15mm, + 22.5mm, + 30mm.
In detail:
- Narrow 680 mm-wide aluminium handlebars for women
- Ergonomic, lock-on B'Twin Sport Comfort grips for good grip and a comfortable feel.

ERGONOMIC WOMEN'S SADDLE: Comfortable and sporty seat

Since your mountain bike rides will get longer and longer, it is important to have a suitable seat designed for women's hips. Our teams have designed an ergonomic saddle which is hollow in the centre to prevent chafing and enhance comfort.
The 31.6 mm aluminium seat post ensures compatibility with most adjustable and suspended saddles on the market.


The E-ST900 electric bike is supplied with B'Twin Flat platform pedals. The pedal surface is wider and the dots more pronounced to better keep the foot on the pedal.


Your E-ST900 mountain bike is supplied with a bell, lights, wheel reflectors and pedals.
The frame is compatible with:
- front and rear mudguards
- stand
- bottle cage (on the horizontal tube)
- saddle pouch
- rear pannier rack (fixed onto the seat stays or special mounts for wide bikes, 148 mm gap for the rear wheel & 2.8" fat tire)
- child seat

Our advice for your first ride

Tip no.1
When mountain biking, there is always the risk of a fall: don't forget to wear a helmet.
Tip no. 2
A puncture can happen at any time, so always remember to take a repair kit and a 6 mm Allen key for removing your rear motorised wheel.
Tip No.3
If you don't want to stop to drink, bring water in a bottle or water bladder to access it while riding.

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Composition / advice

Frame (for bike)
100.00% Aluminium 6061
Stock advice Store your bike in a warm, dry place away from corrosive products and salty air. Never store with the battery flat, and remember to recharge it at least once every six months.
Restricted use : Don't forget to remove the battery to handle the chain.
instructions To get more information about this product, please read instructions
Legal notice Your bike's weight may vary due to tolerances in the components. To make your wheels last longer, we recommend not exceeding the maximum weight of 120kg (rider with mountain bike).

Our commitments

Test Product Our engineers always have real riders test all our products in real conditions. These tests round out our lab tests and let us validate all our products before they hit store shelves.
Guarantee : Lifetime (frame, stem, handlebars). Availability of spare parts: 2 years.Guaranteed for 500 charges.

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E-ST 900 Women's Electric Mountain Bike - 27.5+
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