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Rockrider ST900 Mountain Bike 20" Kids 3'11" to 4'5"
20-inch bike with 6 speeds, front suspension, double disc brake
See shipping rate at checkout
Final Sale: No returns or exchanges
See our return rules for heavy items
Free pickup
San Francisco, 735 Market St. Options
Select an available color and size to see options.
Product Videos
Product Features
Easy to use
6 speeds, quick-release saddle, quick-release front wheel
Bike safety
Double disc brakes provide powerful and easy braking.
Shock absorption
Suspension fork.
Lifetime warranty
B’Twin offers a lifetime warranty on the steel frame, stem, and handlebar.
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Product Customer Reviews
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Good value for money
Bikes not possible to buy in store (even at btwin village) so order and delivery in store Upon receipt I ask this one was adjusted and checked I was told yes First use on my son's birthday and the surprise nothing have to adjust correctly and worst of all not tighten the pedal which causes the loss of it during the first ride with the added bonus of a fall for my son Thanks to the guy who told me yes everything is ok In conclusion good bike and perfect for the practice just remember to have it checked in front of you on site in the store
They set it up in the store. The gear shift, the brakes and everything works great. My son is delighted with his bike.
Just deflating front tire
Great
Very good wheel.
Mountain biking very well equipped and of good quality. Child 5 years 114cm, handles well. Effective with side wheels. Very satisfied
Excellent and light bikes for my 7 year old son who is very happy with the performance of the bike and rides it every day for free time.
in general a good product, perhaps it could have cost a little less.
Perfect
The bike is very beautiful and light Impeccable braking Top!
Brake and derailleur not properly adjusted. Good bike.
Disappointed with the assembly 1st right pedal output not tight (assembly made in store) and a bowl for my son in the woods fortunately there was the helmet… 2nd left pedal output And now with correct use the rear brake which blocks the bike high-end in its category not necessarily interesting
Did I get the wrong batch? Problem with braking, shifting, the gear selector pointer, and the icing on the cake: the pedal falling off during a hike!
Just an adaptation time .... otherwise it's a great bike
Size Guide
Additional Product Information
Composition
Bike frame: 100.0% Aluminum
Frame
Aluminum frame designed by B'Twin. The lowered frame geometry makes it easier to get on and off the bike.
Drivetrain
6 speeds. Ultra-soft grip shifter for kids: Change gears using a grip shifter, which is easier and safer (kids don't have to let go of the handlebar to change gears). B'Twin chose this shifter as it is extra soft and specially sized for kids' hands.
Handlebar / stem / steering
Mid-rise stem and handlebar.Quick-release saddle. Comfortable, reinforced (plastic shell) saddle that provides a comfortable position. Fast, tool-free saddle adjustment. B'Twin selected this reinforced saddle for its tried-and-tested durability (should the bike fall over, for instance).
Brakes
Very reliable double disc brakes. B'Twin chose to equip this bike with a double disc Brake system for its ease of use, easy maintenance, and greater braking power.
Warranty
Lifetime warranty on manufacturing defects for all metal frames, rigid forks, stems, and handlebars.5-year warranty on all carbon frames and forks.2-year warranty on all other parts.Excludes damages arising from normal wear and tear, misuse, negligence, and unauthorized modifications.
Compatible accessories
KIDS BIKE STAND 100 (Model Code 2694189)20” & 24” KIDS BIKE STABILIZERS (Model Code 8550741)
Guarantee
Lifetime (frame, stem, handlebars). Availability of spare parts: 2 years
Origin
Imported
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
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State-of-the-art production processes
minimize manufacturing costs
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Optimized supply chain
reduces retail prices
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Minimal retail footprint
lowers overhead and indirect costs
Rockrider ST900 Mountain Bike 20" Kids 3'11" to 4'5"
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Heavy products return policy
If you return a product you will receive a refund for the purchase price plus any applicable sales taxes, less any non-refundable charges.
Decathlon will cover all shipping costs associated with your return except for items excluded from our return policy such as bikes, basketball hoops, snowboards, surfboards, tents, and other larger / heavier items.
Return costs for heavy products:
| Weight Thresholds | Shipping within California | Shipping outside of California |
|---|---|---|
| > 9 lbs | $20.00 | $25.00 |
| > 30 lbs | $50.00 | $65.00 |
| > 100 lbs | $100.00 | $125.00 |
| > 200 lbs | $200.00 | $230.00 |
If you return a product at any of our store locations, we will gladly help you find the best alternative product or refund you on the spot.