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Rockrider ST 520 Mountain Bike 27,5"

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Model: 8511143

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Product Features

A photo of the Rockrider ST 520 Mountain Bike 27,5" in use

Rockrider ST 520 Mountain Bike 27,5" is designed for regular sporty mountain bike rides.

Raised position., stem can be raised up to 1.18 in., ergonomic saddle: comfort that also yields greater efficiency. 27.5" wheels, double disc brakes, 24 speeds.

Cycling comfort

Raised position. Ergonomic saddle. Height-adjustable stem. Soft-touch grips.


CGF Evo aluminum frame. 24-speed SRAM X3. Light, 27.5" Aero Trail Evo wheels.


Dual disc brakes. Easy handling frame geometry. Tires have good grip in turns.

Easy to use

Innovative fork with easy adjustment based on rider's weight.

Product Customer Reviews

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Rockrider ST 520 Mountain Bike 27,5
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คุ้มค่า คุ้มราคา

ได้ชุดขับ SRAM X3 ปั่นสนุก เกียร์แม่น น้ำหนักกลางๆ แต่คุณภาพโอเค

B’TWIN Rockrider 520

I bought this for my 11 year old son and he’s very happy with it. It’s sturdy, just the right weight for him and it has 8 gears so he’s able to increase his riding speed.

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520 Mountain Bike

Good Basic bike, SRAM gear set works well. Lighter than expected.

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Hi Mr Warrenn

Thank you for your kind review.
The SRAM X3 is the most entry level of SRAM. For better performance and durability, you can check the entire range of SRAM products on their website.
Unfortunately we are not the distributor of SRAM. SRAM can be found at leading Cycling Stores.

Mountain Bike Sport Leader
Excellent bike and Very Good Customer Service

I like the bike so is cheap and good.

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Hi Mr Nazri

Thank you for your kind review.
We hope you find the bike suitable for your needs.

Mountain Bike Sport Leader

Ligera en su desplazamiento tanto en cuidad como en caminos de montaña. La suspensión cumple su función en caminos accidentados tanto en descenso como en ascensos... El juego de cambios sin problema alguno! Muy recomendable sin duda alguna!

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Una compra muy valiosa

Excelente equipo, la supsension es muy buena, fácil de transportar, sin lugar a dudas la volvería a comprar.

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En el primer día se barrió el pedal y después se le salió la llanta .

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Hola Mayra,

Gracias por permitirnos ser parte de tu vida deportiva.Lamentamos tu insatisfacción en cuanto a la experiencia de nuestro producto.Te recomendamos darle vida a nuestra política de satisfecho o satisfecho y regresarlo a la sucursal dónde lo compraste con tu ticket de compra o tu correo de registro, de esa manera podremos hacerte el cambio contara otro producto más adaptado a tu necesidad o a que te lo reparen en nuestro TALLER.

¡Tu opinión es sumamente importante para nosotros, gracias!


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Size Guide

Size Guide Visual

Additional Product Information


Bike frame

  • 100% Aluminum


The RockRider 520 was designed and created in Suzhou, China, by a team of experts and cycling enthusiasts dedicated to designing our MTB Sport Touring line. Production was also done near Suzhou to be as close to our Decathlon stores as possible.


Rockrider CGF Evo (Comfort Geometry Frame) 6061 aluminum frame for 27.5" wheels. Comfortable seating position thanks to raised steering. Seat is 5 times more flexible than a standard frame thanks to a narrow 1.07-in. seat post. Low bottom bracket: helps keep the mountain bike stable in turns, and makes it easier to place foot on the ground. Open steering angle (69.5°): keeps mountain bike stable while riding. Short rear wheel base: bicycle is easy to turn. LIFETIME WARRANTY on the frame!

Front suspension

B'Twin U-Fit 80 fork, with 3.15 in. of travel and an innovative fork stiffness adjustment based on the rider's weight (121 to 230 lbs.). Durable thanks to the materials and fabrication processes used. Equipped with a mechanical spring and elastomer stoppers for maximum reliability and minimum maintenance.

Rear suspension

No rear suspension.


SRAM S200 triple-chainring chainset (22/32/42 teeth). SRAM X3 8-speed rear derailleur. Microshift MS22 front derailleur. SRAM X4 shifters with speed indicators. SRAM PG820 cassette, 8 cogs, 11 to 32 teeth.


Tektro aluminum brake levers: lightweight and precise. Front and rear Hayes MX5 mechanical disc brake calipers: powerful, progressive braking, even in rainy and muddy conditions.


B'Twin Sport Oversize aluminum handlebar; 25.9 in. (Size S and M), and 26.7 in. (L and XL). Exclusive B'Twin aluminum stem, 70 mm (size S and M), and 80 mm (size L). Stem can be raised by up to 1.2", with 5 settings (+0", +0.3", +0.6", +0.9", +1.2"). Semi-integrated A-headset—better sealed and integrated style. B'Twin Sport handles with grooves, 4.72 in. long: genuine comfort while riding.


Aero Trail Evo aluminum wheels with double-walled rims: lightweight, stiff, and durable. 27.5" diameter: the best balance of comfort and performance. Designed with 28 spokes to reduce weight while still ensuring rigidity and strength.


Exclusive B'Twin All Terrain Dry 27.5" x 2.0 tires with a central tread specially designed for fast performance. Side lugs provide traction in turns. Also includes a chart showing recommended pressure levels depending on the rider's weight (see markings on tire sidewalls).

Saddle / seat post

Exclusive B'Twin Ergofit Evo saddle offers outstanding comfort thanks to its wider "Hammock" cut and good distribution of pressure points regardless of the rider's pelvis width. B'Twin Sport seat post in aluminum for less weight. 1.1". diameter provides the seat with a natural flex that's 5 times greater than a classic seat post. 400 mm long, offering a broad adjustment range.


Bicycle comes with mountain bike platform pedals with bearings, made from hard resin for lower weight and greater safety (less aggressive in case of pedal that slips).


31.63 lbs in S without pedals. 31.8 lbs in M without pedals. 32.1 lbs in L without pedals.


Frame can take a bottle cage, saddle bag, mud guard, stand, pannier rack.

User guide & bike assembly

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Warning - california prop 65

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Product testing

We also recommend that beginners wear cycling shorts with a protective pad and/or a gel saddle cover to reduce soreness.

Storage instructions

Store in a cool, dry place, away from corrosive products and salty air.

Superior quality. Unbeatable prices.

For 40 years, Decathlon has delivered the best value in the retail sports industry by offering high-quality, sustainable and cost-effective products.

Decathlon makes the difference
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