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27.5" Mountain Bike Disc Brake

Sale price: Dhs. 1,700.00 Regular price:
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Sale price: Dhs. 1,700.00 Regular price:
Model: 8602020

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Product Features

27.5" Mountain Bike Disc Brake : This 27.5" mountain bike has been designed and developed to best suit getting started with mountain-bike touring in dry weather, for rides of up to 90 minutes.

Change speeds easily on this efficient and easy-to-handle ST 120 mountain bike. You will feel the precision and lightweight provided by the single chainring (1x9 speeds) and mechanical disc brakes.

A photo of the 27.5" Mountain Bike Disc Brake in use

Cycling comfort

Enjoy touring: raised position, 80 mm suspension, hammock saddle, FLEX seat post

Ease of use

Adjust your speed without thinking: 9-speed single-chainring drivetrain.

Directional control

Control your trajectory: cable disc brakes, tyres with side knobs


Pedal efficiently: light aluminium frame, 9 speeds and fast tyres.


An ultra-strong MTB: welded saddle, double-wall rims.

Lifetime warranty

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

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Product Reviews

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2229 reviews

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Great bike

Purchased for my son. So far so good after 6 months of daily use.

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Good quality bike

Lovely bike. Purchased for 11 year old daughter. Good quality and easy to use

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Great bike

I am very pleased with bike & a very good price, as always good service from DECATHLON.

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MTB ST 120

After few kms looks very good,gears,brakes ok..i hope this bike will good like model rockrider 100.10 000 km without problems..Just punctures...

Excellent customer service experience

Fantastic service great customer service experience, swift, polite and friendly staff very professional.

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Mr ste crook

Good product

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Size chart was a bit off and jumpy gears.

Thought it would be a good hybrid/get around bike for the price but once it came realised it wasn't. Disc brakes were rubbing, which I get is usual but still annoying. I am 180cm so opted for size large which on the sizing chart says goes up to the height of 184cm but the seatpost was on max height for me to fit on it properly. Also, the gears jumped around alot under any sort of pressure, and living in a hilly area this was a nightmare. The gears also jumped occasionally when I was just cruising. In just 50 minutes of riding it - I gave up and am trying to get a refund; not a good experience.

Happy with bike

Nice and easy to adjust handlebars / leavers / seat. Gear change and brakes work great with no effort needed .

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Will they continue to manufacture?

Hi everyone! How are you? I would like to know if they will continue to make this bike and if they will make it in size “S”

Pay for what you get

Bike rides very well and can't fault it other than the front forks have massive amount of play and knocking noise. Been told my decathlon "expert bike team" it's perfectly normal and it's just how the bike is. Seems as it's not stated anywhere on the descriptionI would let people know how bad the front forks are.

Mountain Bike for my Son

Bought this for my son for Xmas. Great quality bike and value for money too. I chose the click and collect option as delivery to home wasn't that easy. This comes with the bonus of having it all set up and put together by them at the store. Not an issue for me as a mechanic by trade but just easier to collect. Another bonus is the free 3 month safety check I know a good quality product when I see one and would highly recommend this and also the company and the staff too. The bike was ready for pick up when estimated and the staff were really helpful and friendly. Had a couple of other questions about another bike which they were more than willing to help me with too 10 out of 10 for the ordering process and delivery 12 out of 10 for the helpful friendly staff that I dealt with


Fab for the money

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Mr williams

Great bike the decathlon staff were excellent with me thankyou

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Brilliant Bike

For the money you can’t fault it.

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Additional Product informations



  • 100% Aluminium

Which is the right size?

Several sizes available:S: between 1.50m and 1.64mM: between 1.65 m and 1.74 mL: between 1.75 m and 1.84 mXL: between 1.85m and 2.00mTo 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 the foot on the pedal in the lowest position.3/ If you're between two sizes, choose the larger size.

Unisex frame

With a heavily sloped top tube and a wide range of sizes (from S: 1.50 m to XL: 2 m).The ST 120 mountain bike frame is UNISEX.The ST 120 mountain bike is available with the same frame in a WOMEN'S version: fitted seat, narrower handlebar, shorter stem, fork with a more flexible spring, and brake levers that are closer together.As a WOMAN, if you choose the MEN'S model, we recommend at least purchasing the WOMEN'S SPORT 500 saddle which is fitted to the female form.

A word from the team

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.

A lightweight, comfortable, fun frame

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 rear bases were shortened to make the bike very agile in turns.

Front suspension

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 (55 kg to 105 kg) using the dial on the fork.

Rear suspension: none

This mountain bike has no rear suspension.It is a "semi-stiff" 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; you spend less energy on flat ground.

Derailleur & drivetrain: a single chainring like the pros!

The single chainring is easy and efficient to use: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 while 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

Handlebars, stem, grips

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.

Mechanical disc brakes

The Tektro TKD 68 160 mm double disc brakes provide powerful, progressive braking at the front and rear. The aluminium Tektro brake levers are precise, and easy to hold.The brakes can be applied using only two fingers.3 or 4 sets of 10 dry, intermittent stops are enough to break in your pads.We recommend that you have your brakes checked at least once a year.

27.5" wheels & tyres for dry terrain

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. Their performance is optimised thanks to the rounded central section, whilst the side lugs provide good grip on turns.

Platform pedals

The Rockrider ST 120 mountain bike comes with resin mountain bike platform pedals for lower weight and increased safety.If your foot slides on the pedal, there's less risk of injury.

Transport & storage

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:-300 central stand (ref. 8172767) and 500 central stand (ref. 8172769)-100 bottle cage (ref. 8049106) and 500 bottle cage (ref. 8358133)-Mountain bike mudguard set (ref. 8385291)-100 saddle bag (ref. 8347394) and 500 saddle bag (ref. 8354448)-500 pannier rack (ref. 8364376)-100 frame child seat (ref. 8486913 and 8487125), from size M

Comfort & safety

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.

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