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ROCKRIDER St 520 Mountain Bike, Black - 27.5"

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until £259.99 -%


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

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* From and limited stock
£259.99 -%
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" MTB is designed for MTB rides lasting 2 to 3 hours, all year round. Go faster while controlling your trajectory. The mechanical disc brakes on the ST 520 MTB allow you to confidently take on descents, winding trails, and obstacles.
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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
Directional control Control your trajectory: mechanical disc brakes, tyres with side knobs.
Efficiency Smooth riding: light aluminium frame, 24 speeds and fast rolling tyres.
Durability An ultra-strong MTB: welded saddle, double-wall rims.
Lifetime warranty ROCKRIDER offers a lifetime warranty on the frame, handlebars 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 bike 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 seat 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.


With a heavily sloped top tube and a wide range of sizes (from S: 1.50 m to XL: 2.00 m).
The ST 520 mountain bike frame is UNISEX.
The ST 520 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.


The ST 520 mountain bike was fully designed and developed by our passionate MTB team at the B'Twin Village in France (Lille).
Mountain bikers we talked to expressed their need for control so they can take more risks and continue to improve their technical skills. With that as a starting point, we designed and tested the ST 520 mountain bike, involving MTB riders at every stage.


Our designers created a frame that's easy to get onto.
The CGF frame (Comfort Geometry Frame) EVO is made of 100% aluminium for greater comfort. Its slope was carefully designed to keep your back straighter.


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.
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: the mountain bike is lighter; you spend less energy on flat ground.


3 x 8 speeds, 24 speeds total!
2 shifters on the handlebar.
Left (chainrings): control ascents/descents.
Right (speeds): more precise control over your pedalling.
In detail:
-ROCKRIDER FC ATB 500 triple chainring - 22/32/42 teeth
-SHIMANO ALTUS front derailleur
-MICROSHIFT RD-M46-L rear derailleur
-MICROSHIFT TS39 shifters
-SHIMANO 8-speed cassette (11-32 teeth)
-KMC Z7 wide and sturdy chain


The adjustable stem brings the ST 520 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:
- 680mm oversize ROCKRIDER SPORT aluminium handlebar
- ROCKRIDER SPORT "soft touch" ergonomic grips for good grip and a comfortable feel.


The ST 520's saddle fixing (welded) prevents any saddle movement as you cycle.
Because your comfort is our next priority after 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, either 350mm or 400mm long (according to the bike size). Its reduced diameter of 27.2mm provides your seat with natural flexibility, 30% more than a standard solution.


The Tektro TKD 68 double disc brakes provide powerful, progressive braking at the front and rear. The aluminium Tektro brake levers are light, precise, and easy to hold. The brakes can be applied using only two fingers.
We recommend that you have your brakes checked at least once a year.


The 27.5" wheels of the ST 520 are tolerant and sturdy, with 19 mm double-walled rims with 28 spokes. Overcome your first obstacles without fear: small rocks, cracks, holes and bumps!
Because your first tours 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.


The Rockrider ST 520 mountain bike comes with flat mountain bike pedals made from hard resin for lighter weight and greater safety.
If your feet can slide off the pedals when needed, there's less risk of injury.
The pedals on the ST 520 are compatible with toe clips.


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


Your ST 520 mountain bike is supplied with a bell, lights, wheel reflectors and pedals.
The frame is compatible with:
- Front and rear mudguards
- Stand
- Bottle cage
- Saddle bag
- Rear pannier rack
- Child seat


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: 14.35 kg
M - 165-174cm: 14.45 kg
L - 175-184cm: 14.55 kg
XL - 185-200cm: 14.7 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).
How to maintain and repair your product

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, handlebars). Availability of spare parts: 2 years.

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