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ROCKRIDER ST 120 Mountain Bike, Black/Blue - 27.5"

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until £249.99 -%


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

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£249.99 -%
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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This 27,5" mountain bike is designed for getting started with mountain bike rides in dry weather (rides lasting up to 1.5 hours). An efficient, easy to handle MTB! Riding the ST 120 MTB you will feel the precision and light weight provided by the single chainring (1x9 speeds) and mechanical disc brakes. Change speeds easily!
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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

Cycling comfort Enjoy touring: raised position, 80 mm suspension, hammock saddle, FLEX seat post
Ease of use Adjust your speed effortlessly: 9-speed single-chainring drivetrain.
Directional control Control your trajectory: cable disc brakes, tyres with side knobs
Efficiency Pedal efficiently: light aluminium frame, 9 speeds and fast tyres.
Durability An ultra-strong MTB: welded saddle, double-wall rims.
Lifetime warranty ROCKRIDER offers a lifetime warranty on the frame, handlebar and stem.

Technical Information


Several sizes available:
S: between 1.50m and 1.64m
M: between 1.65m and 1.74m
L: between 1.75m and 1.84m
XL: between 1.85m and 2.00m
To adapt the MTB to your height and size, try these tips:
1/ Sitting on the saddle, you should be able to touch the ground with the tips of your toes.
2/ To adjust the saddle height, your knee should be slightly flexed with your foot on the pedal in the lowest position.
3/ If you're between two sizes, choose the larger size.


The ST 120 MTB has a UNISEX frame.
The ST 120'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 (S: 1.50m to XL: 2m). The ST 120 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.


Our team of mountain bike enthusiasts created this ST 120 mountain bike at our B'Twin Village in Lille, France.
Recreational mountain bikers told us they wanted comfort, effectiveness and durability. Based on that, we designed and tested the ST 120 mountain bike, involving MTB riders at every stage.


Our designers created a frame that's easy to get onto.
The 100% aluminium CGF frame (Comfort Geometry Frame) is both comfortable and easy to handle. The slope angle has been designed to keep your back straight, while the low bases were shortened to make the bike very agile in turns.


The 80 mm front suspension helps you get started with overcoming obstacles on slightly uneven trails easily.
Easily adjust the hardness using U-Fit technology (weight adjuster). Simply set the number to your weight using the dial on the fork.


This mountain bike has no rear suspension. This is a "semi-rigid" mountain bike: perfect for beginners launching themselves into their first mountain bike touring rides. Compared to a full suspension mountain bike (with rear suspension), the advantages are clear: this mountain bike is lighter; less energy is lost on flatter ground.


A single chainring is easy and efficient:
1 chainring and 9 speeds.
Accelerate on the flats and easily tackle the climbs.
With a single lever on the handlebar, you can change gears without hardly thinking!
-ROCKRIDER FC ATB 100 - 32-tooth single chainring equipped with 2 chain guides (anti-derailment)
-MICROSHIFT RD-M46-L rear derailleur
-MICROSHIFT SL-759 right shifter
-MICROSHIFT H092 9-cog cassette (11-36 teeth)
-Wide, sturdy KMC Z9 chain


With a stem that tilts 10° upwards, the riding position of the ST 120 is raised, accessible, and comfortable. In detail:
- 90mm aluminium stem with an angle of 10° for maximum comfort
- 640mm wide steel handlebar for stability and control
- "Soft touch" lamellar grips for a firm yet soft and pleasant grasp.


The saddle of the ST 120 is welded to prevent any movement of the saddle.
And because your comfort is our priority after your safety, we've added an exclusive wider Ergofit saddle with a hammock shape.
Easily adjust the height of your saddle with the Flex steel seat post (350mm or 400mm long depending on the bike size). Its smaller 27.2mm diameter provides your seat with natural flexibility, 30% more than a standard solution.


The Tektro TKD 68 160 mm double disc brakes provide powerful, progressive braking at the front and rear. The aluminium Tektro brake levers are light, precise, and easy to hold. You can brake with just two fingers.
Try to get your brakes adjusted at least once a year.


The 27.5" wheels of the ST 120 are tolerant and sturdy, with 19 mm double-walled rims with 28 spokes.
Start overcoming obstacles fearlessly, including small rocks, cracks, holes and bumps!
Because your first rides will be on dry ground, the Dry 27.5 x 2.0 tyres are most suitable. The central section has low rolling resistance (faster), while the side lugs provide good grip on turns.


The Rockrider ST 120 mountain bike comes with resin mountain bike platform pedals for lower weight and increased safety.
If your foot can slip off the pedal, you're less likely to injure yourself.


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.


The ST 120 mountain bike comes with a bell, lights, wheel reflectors, and pedals.
The frame is compatible with:
- Front and rear mudguards (Flash MTB or MTB 700)
- Stand (500 Adult Base)
- Bottle cage
- Saddle bag
- Rear pannier rack
- Child seat (depending on the model)


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 check of your bike. Just come to your nearest Decathlon workshop with your Decathlon card and/or receipt.


To ensure components last longer, we recommend a maximum load of 120 kg (rider and MTB included).


S - 150-164cm: 15.1 kg
M - 165-174cm: 15.2 kg
L - 175-184cm: 15.3 kg
XL - 185-200cm: 15.5 kg
Weight without pedals.

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Composition / advice

Frame (for bike)
100.00% Aluminium
Stock advice 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.
Restricted use : Not suitable for XC, All Mountain, Enduro and BMX.
Legal notice To ensure components last longer, we recommend a maximum load of 120 kg (rider and MTB included).
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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, handlebar). Availability of spare parts: 2 years.

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ST 120 Mountain Bike, Black/Blue - 27.5
Maintenance and repair
Maintenance and repair
Spare parts