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Rockrider ST500, Kids' Mountain Bike, 20"

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Sale price: $299.00 Regular price:

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Model: 8549159

Product Features

A photo of the Rockrider ST500, Kids' Mountain Bike, 20" in use

Rockrider ST500, Kids' Mountain Bike, 20" is designed for We have designed this mountain bike for children ages 6 to 9 (3'11" - 4'5" tall) who go mountain biking regularly.

To ensure riders can easily overcome rough terrain, we've equipped this 20-inch MTB with a suspension fork. Easily overcome hilly paths with the 6 speeds.

Easy to use

Equipped with a grip shifter to easily change gears (6 speeds).

Brake control

New Easy break brake levers are sized for children's small hands.


Suspension fork. Skinwall tires for less weight, with side knobs.

Cycling comfort

A saddle with a sporty design, sized especially for children.

Product Lifestyle Image Gallery

Image Gallery

Rockrider ST500, Kids' Mountain Bike, 20 

Rockrider ST500, Kids' Mountain Bike, 20 

Rockrider ST500, Kids' Mountain Bike, 20 

Rockrider ST500, Kids' Mountain Bike, 20 

Rockrider ST500, Kids' Mountain Bike, 20 

Rockrider ST500, Kids' Mountain Bike, 20 

Rockrider ST500, Kids' Mountain Bike, 20 

Rockrider ST500, Kids' Mountain Bike, 20 

Rockrider ST500, Kids' Mountain Bike, 20 

Rockrider ST500, Kids' Mountain Bike, 20

Product Customer Reviews

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Rockrider ST500, Kids' Mountain Bike, 20
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Not assembled properly

We bought the cycle just before Christmas and when my son rode the cycle the first day, the handle came out. It was a big red flag for me as my son's safety was compromised. I complaint about it via Messenger and they casually told me it's because of a loose bolt which I can fix myself at home. Upon confronting, they did ask me to come to store and get it fixed. So before you let your kids ride this, please ensure its all good yourself. Also, the bell that came with it was broken.

Hi Vipul,

Thank you so much for your review to us.

We're sorry to hear that our BTWIN 6-9 YEARS OLD 20" ST 500 RR - YELLOW BIKE is unsatisfactory for you.


We take reviews and feedback into consideration as we strive to improve our products to cater to sports users!

We will bring your feedback to our production team to ensure better quality products for you and the rest of our users.


Thank you and I wish you a pleasant week ahead!



Sport Advisor

Nice Bike

Comfortable and nice bike for our 7 years old.

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Hello, Noraidah

Thank you for your review, and we/re glad the product via the perfect rating and we truly believe it has made you feel worthy and of value to spend your money purchasing it. Thank you for your support, and we hope to see you at our stores soon!


Fidah Ngatijan

Sports Leader

Decathlon Singapore

Muy buena bicicleta para iniciar

Antes de usarla hay que revisar que esten bien apretadas todas las tuercas. Tuve la mala experiencia de no hacerlo y la tuerca del manubrio venia flojo y se safo. Afortunadamente el golpe fue leve ya que apenas iniciaba el pedaleo cuando el manubrio se safo.

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Muy satisfecho

Las opciones eran varias y se nos asesoró sobre cuál sería la mejor.

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Muy ligera

Recomiendo esta bicicleta, muy ligera y la suspensión muy suave

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Size Guide

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Additional Product Information


Bike frame

  • 100% Steel

Frame designed for mountain biking

Our engineers have designed a new sturdy steel frame. The frame's rear chainstays are short, making the bike responsive and easy to handle.

Front suspension to cushion unpredictable terrain

Take on new challenging terrain (roots, stones, gravel, etc.) with ease thanks to the travel of the front suspension fork.

Changing gear

This bike is equipped with a grip shifter to change between the 6 speeds: It's safer and easier for children as they don't need to let go of the handlebar to change gears. This makes changing gears to match the terrain simple and easy!

Controlled braking

2 V-Brake pads for effective braking. These brakes are composed of calipers that exert more or less pressure on the rim to slow or stop the rotation of the wheels.

A reinforced, ergonomic saddle

A saddle with a sporty design, designed with care to adapt to the morphology of children. It is equipped with a plastic cover at the back (a bumper) to protect from any impact.


The new chainset has a 140 mm crank that is designed for a child's leg length. This chainset allows you to start pedaling more easily. The crank is covered to prevent the child from coming into contact with the metal part. The double chain guard prevents the chain from derailing.

Riding position

When mountain biking, it is important to control your path. To make it easier for children to learn, our engineers installed a handlebar and stem that are combined into a single steering block. This eliminates the needs for adjustments, so they can stay focused on the road!

20" wheels and mtb skinwall tires

The tires are designed for mountain biking. The lateral lugs provide good grip on turns. The tires are made with SkinWall technology. This process reduces their weight and makes them more flexible, which increases performance, grip and comfort. The recommended tire pressure is indicated on the side of the tire (2 to 3.5 bars). 20" inner tube, 1.7" to 2.2" Schrader valve.

Bike accessories

This MTB is equipped with a bell, lighting, wheel reflectors and platform pedals. The frame is also compatible with other B'Twin accessories: - front and rear mudguards - stand - bottle cage - saddle bag - stabilizers

Dimensions of the bike ready to use

Length: 55.1". Height: 31.5". Width: 21.3".



Storage instructions

Store the bike in a clean, dry place. Clean and grease the chain regularly. Our advice for before each ride: inflate the tires to the pressure indicated on the sidewall.


Lifetime (frame, stem, handlebars). Find out more about this bike's warranty.

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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    Research and development

    delivers high-quality cost-effective products

  2. State-of-the-art production processes

    minimize manufacturing costs

  3. Optimized supply chain

    reduces retail prices

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    Minimal retail footprint

    lowers overhead and indirect costs


Size Guide Visual