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27.5" Mountain Bike ST 540

Sale price: 220.000 KD Regular price:
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Size: Select a size
Sale price: 220.000 KD Regular price:
Model: 8500756

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Product Features

A photo of the 27.5" Mountain Bike ST 540 in use

27.5" Mountain Bike ST 540 : This 27.5" MTB is designed for MTB rides lasting 2 to 3 hours, all year round.

Discover the effectiveness and playful side of the ST 540 with its 27.5" double-walled rims, hydraulic disc brakes and simplicity of the 18-speed double chainwheels. All whilst staying comfortable.

Cycling comfort

Enjoy an upright position, adjustable stem, 100mm suspension and hammock saddle.

Directional control

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


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

Ease of use

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

Lifetime warranty

Rockrider provides a lifetime warranty on the frame, stem and handlebar.

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Product Reviews

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2061 reviews

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Great value MtB

Nice bike, well made and easy to build. Great for my 14 yr old son.

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Great bike for on and off road

Bought my first bike for 30 years having had a standard mountain bike with lots of miles on it. I have been very impressed by the ride, quality of the gears and brakes and it’s handling off road is brilliant. One criticism would be would like a brief instruction list as lots of the bits on it you need some guidance with how to use and how to adjust. Overall very happy with the bike and would recommend it .

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Nice bike

Nice bike as you come to expect from decathlon, feels a touch on the flimsy side compared to the 560 i have, but I haven’t had chance to fully put it to the test yet and it may be just as capable of dealing with rocky downhill tracks. Super comfy saddle, great brakes and suspension, wide handlebars that are comfy but not sure I’m a fan for downhill. Smooth gears, good tyres and all in all a decent purchase.

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Amazing bike for me

I have had this bike for just over 3 months and I love it. I use it everyday and have upgraded from my previous rock rider that I had used for 3 years. Rock rider is a reliable brand and this bike is a great representation of the brand’s great quality at a realistic price. I use this bike everyday to get to school and it works really well in all weather conditions. I would definitely recommend this bike as it is awesome and you will definitely get your money out of it.

Great Bike

I've had this bike for about a month now and I love it. Excellent value for money, I have ridden it on a real mix of terrain and it handles really well on everything so far, very pleased with it.

Used to be great

I've had this bike for a little over a year now, and aside from an upgraded stem and bars, i have kept everything stock. I took it in for one service, where the mechanic failed to spot a basic issue with how my gears were indexed, was unable to fix it, prompting me to spend more money at a local bike shop. About 3 weeks ago (almost one year to the day) the whole bike began to fall apart. When it was taken to said local shop, i needed a new bottom bracket, new breaks, and whole new gearset. The cost of all these repairs is basically as much as i had to pay for the bike. before this, it had been really enjoyable to ride, but now im looking at just buying a whole new bike, off a competent brand, and moving past this whole ordeal

Rockrider st540

Good bike for the value of money. Gears are a little bit clunky and noisy. But, Its a great looking bike and the front suspension forks are good. So far, the tires seem durable and the bike is light to carry. Ive had fun riding this bike overall and the wide handlebars are ideal for me.


Great bike!! Worth it! A big thank you!! to Mick from Sheffield Store.

Great bike

Had it 7 months now, no point reviewing too soon. Came from a giant revel, canot beleive how much more fun this is, light, responsive with really good equipment. Highly recommend especially for the price,


Good road bike

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Cool bike

When they drive to Russia

Not great

Had it for a couple years and the forks go solid after 30-40 mins of riding and the lockout and adjustables on the forks don’t change a thing. The brakes also need bled constantly and aren’t great

Great bike

Buy from store. I ordered mine online after store promised me it would be fully set up.. ended up paying local bike shop to set up as journey back to decathlon store was economical. Also upon delivery brake lever was scratched. Decathlon did credit some money back for damage which was very acceptable

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Rockrider st 540

I've bought this superb mountain bike for my Grandson for Christmas as I didn't want to loose out to one nearer Christmas .

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St 540 rockrider

Very nice bike my grandson loved it great value for the price seems good quality but time will tell comes with lights and a free bike check after staff very helpfull at the Milton Keynes branch

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Hello Robert

We're glad your grandson enjoyed our bike and that you received good service.

We thank you for taking the time to leave a positive review and hope to see you again soon.

Decathlon Milton Keynes

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Additional Product informations



  • 100% Aluminium 6061

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 1.85 m and 2.00 mIf 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).

Unisex frame

With a heavily sloped top tube and a wide range of sizes (from S: 1.50m to XL:2.00m).The ST 540 mountain bike frame is UNISEX.The ST 540 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

The ST 540 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, powerful hydraulic disc brakes, 100mm travel in the fork to easily ride over obstacles, and simple and effective double chainring,...MTBers have been involved at every stage of this bike's development process.

A comfortable, playful frame

For less weight and more efficient pedalling, the Rockrider ST 540 MTB frame is made from 6061 aluminium (only 2.1 kg in size M).Our designers created this bike to be comfortable and easy to manoeuvre. Its slope has been designed to keep your back straighter. The lower bottom bracket helps keep you more stable during turns.

100 mm front suspension

Ride over obstacles with the hydraulic fork. Its 100 mm travel allows you to calmly overcome more obstacles (roots, pebbles, stones, mud).Its built-in lockout system helps to prevent bobbing and loss of speed on faster terrain.

Rear suspension: none

This mountain bike has no rear suspension.This is a "semi-rigid" mountain bike. 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. If however your primary concern is comfort and manoeuvrability, the ST 540 is available in a full suspension version with suspension at the rear.

Double chainring derailleur and drivetrain

2 9-speed chainwheels 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

Handlebars, stem, grips

The adjustable stem brings the ST 540 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.


Our teams designed and created an exclusive ROCKRIDER ERGOFIT saddle. Designed for all hip widths, its hammock shape is very comfortable for long, athletic rides. The Flex 27.2mm diameter aluminium seatpost also contributes to its increased level of comfort.Quick and easy tool-free adjustment of your saddle height using the adjustment lever on the seat post clamp.

Hydraulic disc brakes

No matter what conditions you ride in (dry/wet), the Rockrider by Tektro 160mm double hydraulic disc brakes 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.

27.5" wheels with double-walled rims and all-condition tyres

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

Easily transport and store your mountain bike

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 mountain bike is fitted with a bell, lights, wheel reflectors and pedals.The frame is compatible with:-500 chainstay stand (ref. 8302792)-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), whatever the size

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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