27.5 Inch Electric Mountain Bike E-ST 500 - Black/Blue


This 27.5" electric mountain bike has been developed by us so that you can get away and experience the fun of mountain-bike touring, even in very hilly areas.

Easily take on any terrain with this electric mountain bike, thanks to its torque motor. Its 420Wh battery means that you can extend your outings. All parts are designed for greater durability.

Color: BLACK / Pacific blue

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Product benefits


Overcome your first slopes with the motor's torque of 42Nm at 250 W.


Ride an average of 2.5 hours at a sporty pace thanks to the 420Wh battery.

Smooth pedalling

Pedal naturally with its integrated torque sensor.

Cycling comfort

Enjoy touring: raised position, 120mm suspension, Ergofit hammock saddle

Directional control

Manage your path: hydraulic fork, wide tyres and handlebar.

Technical information

Which is the right size?

Several sizes available:
S: between 1.50m and 1.64m
M: between 1.65 m and 1.74 m
L: between 1.75 m and 1.84 m
XL: between 1.85 m and 2.00 m

If you are 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 +300%, helping you ride over obstacles.
You'll get to enjoy longer MTB rides.
The motor stops providing electrical assistance when you stop pedalling.
The walking mode offsets the mountain bike's weight when you need to walk your bike.


We created this E-ST 500 mountain bike at our B'TWIN VILLAGE (Lille, France) especially for mountain biking enthusiasts.
We have designed and tested the bike E-ST 500, involving riders at every stage of the project.


The frame of the Rockrider E-ST500 EAMTB has been designed using 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 motor on the rear wheel was co-developed with VISION for mountain biking:
- a torque of 42Nm to overcome your first slopes
- a wheel axle of 150x12mm to stand up to rough terrain
- watertight bearings to withstand environmental conditions which can sometimes be tough.
What if you get a puncture? 8 Mm Allen key a needed to unscrew the wheel nuts. This tool is available in our 900 multi-purpose tool/bike multi-tool.


Our battery is equipped with battery cells from LG or Samsung, (LGC-MG1 or SDI), which are known 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".


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.
There is also a lock in case you want to stop your battery getting stolen. For example, if you park your bike in the street.


A discreet LCD control screen. It is located just to the side of your left grip, so you can choose between the 3 assistance modes without letting go of the handlebars: (Deactivated), Economy, Standard, and Boost.
You'll also find a host of useful information:
-Current speed
-Average speed
-Maximum speed
-Distance covered
-Total distance
-Battery level
-Remaining battery range (in km)
-Active assistance mode


How do you control your speed, particularly on technical sections? We have integrated a torque sensor into the bottom bracket of the E-ST500 EAMTB. This allows you to control the level of electrical assistance in the simplest way possible: by pedalling!
If you push harder, you accelerate; if you push less, you'll slow down.


Mode 0 - Deactivated
The battery is not used.

Mode 1 - Economy +50%:
Extend your rides while conserving battery life. Ideal when you want a little push on small gradients.

Mode 2 - Standard +150%:
This is the most versatile mode. Climb any slope without getting too tired and without using too much power.

Mode 3 - Boost +300%


Calmly overcome new obstacles (roots, rocks, gravel, etc.) thanks to the 120mm of travel in the Suntour XCR hydraulic fork.
Our Rockrider mountain bike team worked with Suntour to design a superior lubrication and wiper seal for this electrically-assisted mountain bike. This ensures the fork stays sensitive over time.


The E-ST500 electric bike is equipped with a single chainring and SRAM X-SYNC anti-drop technology to prevent chain drops.
A single shifter on the right handlebar makes it easy to shift between the 9 speeds.

In detail:
- Sram X-Sync 32-tooth chainring
- Shimano Altus M2000 9-speed rear derailleur
- Shimano Altus M2000 shifter with gear indicator
- Shimano Altus 9-cog 11-36 cassette
- KMC X9 chain


These wheels were specially designed for this mountain bike:
- 19 mm rim with 28 spokes at the front
- 23 mm rim (distance between flanges) with 36 oversize spokes at the back for more sturdiness and a good hold on wide tyres up to 2.5".
- Cone hub with bearings (easy to maintain) at the front
- Sealed motor bearings at the rear
- TUBELESS compatible at the rear: you'll need rim tape, a TUBELESS tyre, a specific PRESTA valve and tyre sealant.


So you feel safe on any terrain and for traction adapted to your motor, the E-ST500 mountain bike is equipped with Hutchinson Cougar 27.5" x 2.4" tyres. 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 Hayes MX5 cable-operated 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 500 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 have a suitable seat. Our teams have designed the exclusive ROCKRIDER Ergofit Evo 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-ST500 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, 150mm gap for the rear wheel)
- 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 can happen at any time, so always remember to take a repair kit and an 8 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.


To optimise the durability of the components, we recommend a maximum load of 120 kg (rider, kit + bike).
To find out more about usage and maintenance information of the Suntour fork, go to the Suntour website.
There you will be able to download the user manual for your fork.

Care advice

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


Lifetime (frame, stem, handlebar). Availability of spare parts: 2 years.Guaranteed for 500 charges.


S - 150-164cm : 22.1 kg
M - 165-174cm : 22.2 kg
Weight without pedals.

Product concept & technology

Product Composition

Frame 100% Aluminium 6061


Store it 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.

User Directions

Don't forget to remove the battery to handle the chain.


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.


To have more informations about this product, consult the notice


27.5 Inch Electric Mountain Bike E-ST 500 - Black/Blue
27.5 Inch Electric Mountain Bike E-ST 500 - Black/Blue
27.5 Inch Electric Mountain Bike E-ST 500 - Black/Blue
27.5 Inch Electric Mountain Bike E-ST 500 - Black/Blue
27.5 Inch Electric Mountain Bike E-ST 500 - Black/Blue
27.5 Inch Electric Mountain Bike E-ST 500 - Black/Blue



Q:How to assemble your bike?

A: Everything you need to know about making sure your bike is comfortable, secure and ready to ride.

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