Decathlon Rockrider ST100, 21 Speed Mountain Bike, 27.5", Unisex, Red, Large
Decathlon Rockrider ST100, 21 Speed Mountain Bike, 27.5", Unisex, Red, Large
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Decathlon

Decathlon Rockrider ST100, 21 Speed Mountain Bike, 27.5", Unisex, Red, Large

3.9 stars out of 444 reviews
(3.9)|
444 ratings
Decathlon Rockrider ST100, 21 Speed Mountain Bike, 27.5", Unisex, Red, LargeDecathlon Rockrider ST100 21 Speed Mountain Bike 27 5 Unisex Red LargeDecathlon Rockrider ST100 21 Speed Mountain Bike 27 5 Wheels Adult Unisex Red Medium

Key item features

  • It isn't always easy to get the right position on a mountain bike. Our designers created a frame that's easy to get onto. The 100% aluminum CGF frame (Comfort Geometry Frame) is both comfortable and easy to handle. The slope angle has been designed to keep your back straight, while the rear bases were shortened to make the bike very agile in turns.
  • The 80 mm front suspension helps you get started with overcoming obstacles on slightly uneven trails easily.
    Its mechanical spring is a stamp of reliability. And the fork is particularly easy to maintain. To adjust the stiffness? It's a very easy to use a] single dial. 
  • 3 x 7-speed chainrings, 21 speeds total. 2 easy-to-use grip shifters on the handlebar. Left (chainrings): control ascents/descents. Right (speeds): more precise control over your pedaling.
  •  With a stem that tilts 10° upwards, the riding position of the ST100 is raised, accessible, and comfortable. The saddle of the ST 100 is welded to prevent any movement of the saddle. Your comfort is our priority after your safety, we've added an exclusive wider Ergo fit saddle with a hammock shape. 
  • Easily adjust the height of your saddle with the Flex steel seat post (350mm or 400mm long depending on the bike size). Its smaller 27.2mm diameter provides your seat with natural flexibility, 30% more than a standard solution.
  • Two 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 .
  • Thanks to the special design of the ST 100's aluminum brake levers, you only need two fingers to brake.
  • The wheels of the ST 100 are tolerant and robust, with 27.5" double-walled 28-spoke rims (26" for the XS size). Start overcoming obstacles fearlessly, including small rocks, cracks, holes, and bumps!
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Customer ratings & reviews

3.9 out of 5 stars
stars444 ratings409 reviews
How item rating is calculated
  1. 5 stars53% (237)
  2. 4 stars20% (89)
  3. 3 stars8% (36)
  4. 2 stars5% (24)
  5. 1 star13% (58)

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Showing 1-3 of 409 reviews

Dec 8, 2025
Gary
5 out of 5 stars review

Seller Verified Purchase

An excellent bike, reassuring and forgiving

Even after 2000 kms, this bike is as forgiving and reassuring on the road for an old rider like me, as an old friend. The bike is such great value and deserves the excellent online reviews that it has. Decathlon has been wonderful with servicing it, and although not the most beautiful bike on the road it does kind of have a certain handsomeness that grows on you after a while. You can lighten the bike easily with tires, tubes and pedals. Speed wise it gets up and goes when asked to and the brakes are very good (some initial squealing). At speed it is comfortable, stable and reassuring.My suggestion is to take your new bike early on, on a ride with a long downhill, build up some speed and engage both brakes all the way to the bottom to bed them in properly. Any noise will then decrease. 5 stars Decathlon thank you.

Review from decathlon.com
Helpful?fac120f0-0b0c-11f1-8e30-63e7131886fb372288889
Oct 2, 2025
ethan
5 out of 5 stars review

Seller Verified Purchase

excellent 1st bike

i got this as my first bike, its excellent, it can be used for short and long distances. Done my first 100km on it before upgrading. Withstood thousands of km without any issues.

Review from decathlon.com
Helpful?fac120f0-0b0c-11f1-8e30-63e7131886fb372288889
Aug 20, 2020
Walmart customer
4 out of 5 stars review

Verified Purchase

Affordable mountain bike

Worth the price. Was not able to find affordable bike in this year. Got to see how sturdy and durable this bike can last. Overall happy with the purchase

Helpful?fac120f0-0b0c-11f1-8e30-63e7131886fb372288889