27.5" Full-Suspencion Mountain Bike - Blue/Orange


This 27.5" mountain bike has been designed and developed to best suit mountain bike rides lasting two to three hours, all year round, in any conditions.

Control your trajectory even better with the fully suspended ST 540 S bike, with a 120mm fork, air shock, hydraulic brakes, and 27.5" double-walled wheels for guaranteed comfort with a sporty ride.

Color: Pacific blue
Size: size guide


Product benefits

Cycling comfort

Cycling comfort

Enjoy the raised position, adjustable stem, 120mm suspension and hammock saddle

Directional control

Directional control

Control your trajectory: hydraulic fork and brakes, tyres and a wide handlebar.



Ride efficiently thanks to 27.5" wheels, 18 speeds and light tyres.

Ease of use

Ease of use

Lock the fork in one quick step, and adjust the saddle effortlessly.

Lifetime warranty

Lifetime warranty

ROCKRIDER offers a lifetime warranty on the frame, handlebars and stem.

Technical information

Which is the right size?

Several sizes available:
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).


The ST 540 S MTB has a UNISEX frame.

The ST 540's frame has been carefully designed down to the smallest detail, from the top tube's relatively pronounced slope, to the wide range of sizes (M: 1.65m to XL: 2m). The ST 540 S is not only lightweight and comfortable, but UNISEX as well.

To make the most of the improved comfort, the women on the Rockrider team recommend the 500 Women's Sports saddle, which is specially designed for the female form.


The ST 540 S mountain bike was fully designed and developed by our passionate MTB team at the B'Twin Village in France (Lille).

A comfortable, efficient mountain bike: more progressive and powerful hydraulic disc brakes, air shock and 120mm fork to get over obstacles easily, simple and effective double chainring.
Women mountain bikers have been involved at every stage of this bike's development process.


For less weight and more efficient pedalling, the Rockrider ST 540 S frame is made from 6061 aluminium (only 2.7 kg in size M without suspension). Its 120mm rear shock uses a single-pivot system (more sensitive to small impacts, while remaining firm when encountering large impacts) and sealed bearings for a great lifespan.


The hydraulic fork, with 120 mm travel, allows you to easily ride over more obstacles (roots, pebbles, stones, mud).
Steer a precise path with the higher diameter dampers (32 mm).
The fork's built-in lockout system helps to prevent bobbing and loss of speed on faster terrain.


This bike has a light 120 mm X-FUSION E1 air shock that has been specially adapted to fit this frame. You can easily adjust it based on your weight using the Schrader valve, providing you with a very good balance of sensitivity and performance.
A special "high pressure" pump is required to adjust this shock (Rockrider fork and shock pump - ref: 3310286).


2 9-speed chainrings for 18 easy-to-use speeds.
The thru-axle bottom bracket is very stiff and long-lasting.

In detail:
-SHIMANO Altus 22 and 36 tooth double chainring
-MICROSHIFT FD-M462 front derailleur
-SHIMANO Altus rear derailleur
-SHIMANO Acera shifters with speed indicators
-MICROSHIFT H092 9-cog 11 to 36 tooth cassette
-KMC X9 chain


The adjustable stem brings the ST 540 S controls to your hands. The all-aluminium Rockrider stem is 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.


Our teams designed and created an exclusive ROCKRIDER ERGOFIT Evo saddle. Designed for all hip widths, its hammock shape is very comfortable for long, athletic rides. The aluminium Rockrider Sport seat post is lightweight and has a wide adjustment range, with a 31.6 mm diameter and 400 mm in length.

Quick and easy tool-free adjustment of your saddle height using the adjustment lever on the seat post clamp.


No matter what conditions you ride in (dry/wet), the dual hydraulic disc brakes at the front and back will come through for you, even in the mud.
Hydraulic braking adds more power and progressive braking and requires less powerful use of the brake levers.
The aluminium brake levers are easy to grip and precise.


The aluminium wheels are effective and sturdy: 27.5" diameter and double-walled rims. Their diameter is the perfect balance of comfort and performance. With their 28 spokes, they are lightweight, stiff, and durable.
The wide, ROCKRIDER ALL CONDITIONS (60 TPI) 27.5" x 2.1 tyres have side knobs designed for riding on all types of terrain (dry, wet, etc.).
Tubeless Ready 23 mm rims: SCHRADER valves, TUBELESS rim tape, TUBELESS tyres, and puncture-proof liquid to be added.

Platform pedals

The ST 540 S comes with Rockrider Flat platform pedals with a wider pedalling surface and more pronounced dots for better grip on the pedals.


We added a quick release system for easily removing/reattaching the front wheel.
Our advice: a bike rack is an easy way to transport your mountain bike without dirtying your car.


Your ST 540 S mountain bike comes with a bell, lights, wheel reflectors and pedals.

The frame is compatible with:
-Bottle cage with side opening (ref. 8548543)
-Mountain bike mudguard set (ref. 8385291)
-100 saddle bag (ref. 8347394) and 500 saddle bag (ref. 8354448)


Your bike's fittings (chain, derailleur, brakes, etc.) will adjust over time. Take advantage of a free servicing within 6 months after purchase. Our technicians will carry out a 13-point inspection of your bike. Just come to your nearest Decathlon workshop with your Decathlon card and/or receipt.


Lifetime (frame, stem, handlebar). Availability of spare parts: 2 years.


M - 165-174cm : 14.45 kg
L - 175-184cm : 14.55 kg
XL - 185-200cm : 14.65 kg
Weight without pedals.

Product concept & technology

Product Composition

Frame 100% Aluminium 6061


After washing, rub with a dry cloth to remove all traces of moisture. Store your mountain bike in a cool, dry place, away from corrosive products and salty air.

User Directions

Not suitable for XC, All Mountain, Enduro and BMX.


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" Full-Suspencion Mountain Bike - Blue/Orange
27.5" Full-Suspencion Mountain Bike - Blue/Orange
27.5" Full-Suspencion Mountain Bike - Blue/Orange
27.5" Full-Suspencion Mountain Bike - Blue/Orange
27.5" Full-Suspencion Mountain Bike - Blue/Orange
27.5" Full-Suspencion Mountain Bike - Blue/Orange
27.5" Full-Suspencion Mountain Bike - Blue/Orange
27.5" Full-Suspencion Mountain Bike - Blue/Orange

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