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Rockrider ST100, Mountain Bike, 20'', Kids 3'11" to 4'5"

Sale price: $249.00 Regular price:

A sturdy, single-speed, 20" white bike that's simple to ride. Equipped with a bell, it can be ridden around town as well as on trails.

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Size: Select a size
Sale price: $249.00 Regular price:

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San Francisco, 735 Market St. Options

Select an available color and size to see options.

Model: 8628166

Product Features

A photo of the Rockrider ST100, Mountain Bike, 20'', Kids 3'11" to 4'5" in use

Rockrider ST100, Mountain Bike, 20'', Kids 3'11" to 4'5" | Designed for 6 to 8 year old children who are beginning to learn to ride a bike.

A sturdy, single-speed, 20" white bike that's simple to ride. Equipped with a bell, it can be ridden around town as well as on trails.

Easy to learn

Single-speed, simple and efficient bike. Bike weight 24.3 lbs.

Bike safety

V-Brakes provide powerful and easy braking.

Lifetime warranty

B’Twin offers a lifetime warranty on the frame, stem, handlebar and rigid fork.

Product Customer Reviews

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625 Reviews
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Rockrider ST100, Mountain Bike, 20'', Kids 3'11
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Mr Mahmood

Pleased with the purchase surprise for my grandson really happy

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Terrible Bike

Within 3 months had spent more time in the shop than being ridden problems with gear,brake,chain etc. Customer service mainly poor to non existent first time purchasing a bike from Decathlon seriously considering contacting consumer trading.


Very helpful staff looking forward to other visit when the time comes!!!

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Very Professional

Ordered this bike online as an xmas present for my grandson. Travelled to the Oxford store expecting to pick up a box that i would assemble myself at home. I was very suprised when the staff member wheeled my bike out slready assembled. I was then advised on the merits of he 20inch frame, how to adjust everything, and offered to fit the mudguards i purchased in store. Was also given a full brief on the returns policy if i wasnt satisfied, and also the contact details for any problems. The bike was excellent. Under £100 but with all the quality and materials of a bike a lot more expensive. I cant fault the bike or the service at Decathlon. I would recommend the shop wholeheartedly. Made my xmas shopping a lot easier.

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Thank you for the review, James! We are thrilled that you enjoyed your time in our store. We hope to see you back in our store very soon.

Christmas present for 7 year old son

Great service, bike is brilliant. So easy to ride!

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Birthday gift

Visited the store in Wandsworth and the staff on the bike section was really helpful in helping me choose the right bike for my sons birthday gift. Very good bike as a first riding solo no stables. Great service in checking before we leave and making sure the bike was up to standards for my son . Very happy and would recommend to others to use and visit this store

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The Bike is amazing - gave my son the confidence he needed to start riding a bike ! Great value, great bike

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Hi Angela,

We are happy to hear that your son's new bike was a success!

Thank you for taking the time to leave your review.

Take care and have a great day!


Sports Advisor (Customer Service)

Decathlon Wednesbury

Decathlon UK Limited. Company number: 03140144. VAT number: GB679262296.

Registered office: 9 Maritime Street, London, SE16 7FU.

Good solid bike

Reviewing after 18 months, bike is excellent and my son is now confident and riding this bike.


I had brought this bike for my little boy and its perfect. The bike was built and it even came with lights front and back. This is the perfect bike for your younger ones to start mountain biking and decathlon staff guiltbrook were fantastic.

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Perfect child’s bike

The bike sizing was exactly as listed, build quality was much better than expected for the price and very little to do in the means of assembly. Very pleased and will buy from Decathlon again.

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Purchased for 5 year old. He loves it, perfect

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great single gear bike


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wonderful mountain bike with a very high quality

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Без степенка

Велосипеда е без степенка и няма налична от този размер, за да си я закупя

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Благодарим Ви за отделеното време и оценката, която сте дали за нашия продукт. Информираме Ви, че нашия Национален център за обслужване на клиенти ще се свърже с Вас за съдействие относно избора на подходяща степенка.

Спортни Поздрави,

Екипът на Декатлон България!

Супер колело на супер цена

Колелото е супер. Малкия го подкара от раз и го кара с лекота. Трябваше да купим допълнително калници и стойка, защото не са включени в базовия модел. Мисля, че е съотношението цена-качество е оптимално.

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Additional Product Information


Bike frame

  • 100% Steel


The chainwheel anti-derailment device and low step-through frame make it easy to get on and off.

Accessories / equipment

Fully equipped for use on public roads (bell, reflectors). The rear derailleur guard protects the derailleur from damage in the event of an impact.



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
  1. product-research

    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

  4. laptop-checkout

    Minimal retail footprint

    lowers overhead and indirect costs