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Rockrider ST500, Mountain Bike, 20", Kids 3'11" to 4'5"
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.
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Free pickup
San Francisco, 735 Market St. Options
Select an available color and size to see options.
About this item:
- Shifter: 6-speed grip shifter.
- Equipped with suspension fork to cushion unpredictable terrain.
- Brakes: Ultra-reliable v-brake system.
- Lifetime Warranty: Frame, stem, and handlebars guaranteed for life.
Product Videos
Product Features

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.
Efficiency
Suspension fork. Skinwall tires for less weight, with side knobs.
Cycling comfort
A saddle with a sporty design, sized especially for children.
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Product Customer Reviews

The tires are not moving freely.
Hello Kshitij,
We are extremely sorry to hear about this. We request you to visit the store with your bike and someone from the bike department will have a look and recommend a tune-up if required. We have a 365 return policy for all the in-store purchases for members & we do a no-questions-asked return/exchange.
Thanks & Regards,
Decathlon Brampton Team
My son loved it
Great value, well made and looks smart. Highly recommend.
I brought for my son 7th Birthday! He love it !
Overall a good sturdy bike.
Got this (from Santa) for my 6 year old. Pedal fell off on first outing! How dyou explain that to a child. Would give 1 star but I’m giving decathlon the benefit of the doubt that maybe this was just an oversight by the ‘elf’s’.
Great price.quality product. Excellent customer service. Thankyou.
Thank you for your kind words, Anthony.
We really appreciate you taking the time to leave us your feedback.
Have a great day and we hope to see you again soon.
Emily
Sports Advisor (Customer Service)
Decathlon Wednesbury
Decathlon UK Limited. Company number: 03140144. VAT number: GB679262296.
Registered office: 9 Maritime Street, London, SE16 7FU.
Looks a good stable bike. Great service from all the staff that was involved with the purchase.
Good
Great bike and first one for my grandson and he loves it
Very good value for money and excellent professional customer service at Decathlon Warrington. I highly recommend this product and this store.
Excellent quality bike (I needed two for my twin grandsons) for Christmas. I had seen bike online and was staying with my daughter in Suffolk when we visited Cambridge Decathlon to look at bikes, I was so impressed by both the bike and the helpfulness of staff I purchased immediately. Alison a happy nan
Very strong bike, but the accessories like mud guards were very flimsey. Buying of helmet fitted when bought within weeks became small and could not extend the straps anymore, The bottle holder recommended does not hold properly, Bit disappointed as this was bought for my Grandsons birthday and he chose the extras which your sales advisor advised.
Brilliant bike shame my grandson has got to wait until Christmas
Perfect
Size Guide

Additional Product Information
Composition
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.
Crankset
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, 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".
Origin
Imported
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.
Guarantee
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.