27.5"+ Electric Semi-Rigid MTB Bike E-ST 900 - Grey

Please note, for size S, the minimum height is 1.60 m and not 1.50 m as indicated in the drop-down menu grid.

If you are on the edge between 2 sizes: Choose the smaller size for easier steering (easier to handle) and comfort (straighter back).
Choose the larger size for easier pedalling with a more stretched out position (position more suited to performance)

You have to pedal to go forward!

The electric assistance boosts your pedalling by 320%, helping you ride over obstacles.
You'll get to enjoy longer MTB rides.
The motor stops when you stop pedalling.
The walking mode compensates for the weight of the bike when you need to put your feet down.

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.

The frame of the Rockrider E-ST900 electric MTB is made of 6061 aluminium with hydroformed tubes. Why? The battery sits snugly on the frame to improve the robustness of this electric mountain bike.
The forged aluminium parts make it compatible with the new 27.5"+ tyre format (wider than the 27.5") in the rear, while remaining easy to manoeuvre. We've kept a frame geometry with short bases for easier steering.

The BROSE T Aluminium central motor is specially designed for high altitude mountain biking:
- 70 Nm torque to handle large obstacles and steep gradients
- metal housing for maximum durability
- belt for an ultra-quiet motor
- and sealed bearings to withstand the sometimes adverse weather conditions of mountain biking

Our battery is equipped with SAMSUNG SDI cells, renowned for their high level of reliability and safety.

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

A discreet LCD control screen. The screen is right next to your left grip so you don't have to let go of the handlebar to choose from the 4 assistance modes available: Eco+, Economy, Standard, Boost.
You'll also find a host of useful information:

-Assistance level
-Battery level
-Speed (current, average, maximum)
-Remaining battery life
-Distance covered (total and trip)

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 slope without getting too tired and without using too much power.

Mode 4 - Boost +320%

Ride over obstacles (roots, pebbles, stones, etc.) easily thanks to the Rockshox JUDY fork with 120 mm of travel.
This fork has:
- a thru axle and conical pivot for more durability.
- pneumatic spring for optimal adjustment based on your weight
- rebound adjustment and lockout for better control, depending on the terrain.

The E-ST900 electric bike is equipped with a single chainring and ChainFlow 3D anti-drop technology to prevent chain drops.
A single shifter on the right handlebar makes it easy to shift between the 10 speeds.
In detail:
- ChainFlow anti-derailment 34-tooth chainring
- SHIMANO DEORE M6000 Shadow+ 10-speed rear derailleur with long cage
- SHIMANO DEORE M6000 right shifter
- SHIMANO DEORE 10-cog cassette (11-42 teeth)
- KMC E10 Turbo special e-bike chain

These wheels were specially designed for this mountain bike:
- 36 mm rims (width between brackets) and 32 spokes at the front and rear for greater durability and a good hold on wide (2.8") tyres.
- BOOST format thru axles (12x148 rear, 15x110 front) for greater durability
- Aluminium hubs with sealed bearings.

- TUBELESS READY rims: you will need TUBELESS tyres, specific Presta valves, and puncture sealant.

So you feel safe on any terrain, and to provide traction suited to your motor, the E-ST900 mountain bike is equipped with Hutchinson Taipan Koloss 27.5+ tyres with a 2.8" cross-section. 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.

The adjustable stem brings the E-ST 900 controls to your hands. The all-aluminium Rockrider stem is 70 mm (size S), 80 mm (size M/L), or 90 mm (size XL) and can be raised to 5 adjustment intervals: + 0mm, + 7.5mm, + 15mm, + 22.5mm, + 30mm.
In detail:
- 720mm oversize ROCKRIDER SPORT aluminium handlebar
- ROCKRIDER SPORT "soft touch" ergonomic grips for good grip and a comfortable feel

Since your mountain bike rides will get longer and longer, it is important to sit comfortably. So our teams designed the exclusive ROCKRIDER Ergofit Pro saddle. It fits all hip sizes and has a curved shape that is particularly good for sport trail rides.

The 31.6 mm aluminium seat post ensures compatibility with most adjustable and suspended seat posts on the market.

The bike comes with 520 Grip MTB platform pedals (ref. 8487130) with a wider pedalling surface and more pronounced dots for better grip on the pedal.However, if you are looking for improved performance when pedalling and better control of the bike when cycling, we recommend replacing them with clipless pedals with platforms or wide aluminium platform pedals.

Your E-ST900 mountain bike is fitted 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
...

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 could happen at any time, so always remember to take a repair kit and a 6 mm Allen key for removing your wheels.

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.

Leave your battery on the bike when washing using a hose. This will protect the connectors from rusting.