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ROCKRIDER ST 100 Mountain Bike, Red - 27.5"

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until £179.99 -%


This price includes a recycling fee for electrical equipment and batteries DecathlonDeeeTaxMentionAfterPrice / Since

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£179.99 -%
This price includes a recycling fee for electrical equipment and batteries DecathlonDeeeTaxMentionAfterPrice / Since

* From To

* Sales from to Until end of stock
* From and limited stock
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Have fun as you tackle small obstacles in the great outdoors, whether it's your first mountain bike adventure or you're still getting a handle of the off-road experience with the Rockrider ST 100. Comfort is the priority - check out the CGF frame with raised position, 80mm suspension, Ergofit hammock saddle with Flex seat post and 27.5" wheels (26" in XS) - but speed isn't far behind (there are 21 and the grip shifters make them quick to switch between).
  • Light frame with raised position for comfort and control
  • Precise breaks and lugged tyres
  • 80mm suspension
Not Available Now

We currently have limited capacity to build bikes in our warehouse. Due to this, we are limiting the number of bikes we sell per day. If you are unable to process your order at checkout, please return the following day to make your purchase.


Product benefits

Cycling comfort Enjoy touring: raised position, 80 mm suspension, hammock saddle, FLEX seat post
Durability An ultra-strong MTB: double-walled rims, welded saddle, derailleur guard.
Efficiency Light frame, 21 speeds, 27.5" wheels (XS 26"), tyres with low rolling resistance
Directional control Control your trajectory: V-Brake pads, tyres with side knobs
Lifetime warranty ROCKRIDER offers a lifetime warranty on the frame, handlebar and stem

Technical Information


Several sizes available:
XS: between 1.40m and 1.54m
S: between 1.55m and 1.64m
M: between 1.65m and 1.74m
L: between 1.75m and 1.84m
XL: between 1.85m and 2.00m
To adapt the bike to your height and size, try these tips:
1/ Sitting on the saddle, you should be able to touch the ground with the tips of your toes.
2/ To adjust the saddle height, your knee should be slightly flexed with your foot on the pedal in the lowest position.
3/ If you're between two sizes, choose the larger size.


With a very marked slope on the top tube and a wide range of sizes (from XS:1.45m to XL:2.00m),
The ST 100 mountain bike frame is UNISEX.
The ST 100 mountain bike exists with the same frame in a WOMEN'S version: adapted seat, narrower handlebars, shorter stem, fork with a more flexible spring, and brake levers that are closer together.
As a WOMAN, if you choose the MEN'S model, we recommend at least purchasing the WOMEN'S SPORT 500 saddle which is adapted to women's body types.


We created this ST 100 mountain bike at our B'Twin Village (Lille, France) especially for mountain biking enthusiasts.
Recreational mountain bikers told us they wanted comfort, effectiveness and durability. Those features were our starting point as we designed, developed and tested the ST 100 mountain bike, with real riders involved throughout the project.


It isn't always easy to get the right position on a mountain bike. Our designers have created an entirely new frame that is easy to step over.
The 100% aluminium CGF frame (Comfort Geometry Frame) is both comfortable and easy to handle. The slope angle has been designed to keep your back straighter whilst the rear has been shortened to ensure the bike is very agile when turning.


The 80 mm front suspension helps you overcome your first obstacles on slightly uneven trails with no worries.
Easily adjust the hardness using U-Fit technology (weight adjuster).Simply set the number to your weight using the dial on the fork.


This mountain bike has no rear suspension. This is a "semi-rigid" mountain bike: perfect for beginners launching themselves into their first mountain bike touring rides. Compared to a full suspension mountain bike (with rear suspension), the advantages are clear: this mountain bike is lighter; less energy is lost on flatter ground.


3 x 7 speed chainwheels, 21 speeds total!
2 easy-to-use grip shifters on the handlebar.
Left (chainwheels): control ascents/descents.
Right (speeds): more precise control over your pedalling.
In detail:
-Triple 22-, 32- and 42-tooth chainring + protection from grease
-Shimano TY500 front derailleur
-Shimano TY300 rear derailleur
-SRAM MRX grip shifters with speed indicator
-Shimano TZ500 7-cog, 14- to 28-tooth cassette
-Wide, sturdy KMC Z51 chain


With a stem that tilts 10° upwards, the riding position of the ST 100 is raised, accessible, and comfortable.
In detail:
- 90mm (in sizes XS and S) or 110mm (in sizes M, L and XL) aluminium stem with an angle of 10° for maximum comfort
- 620mm-wide steel handlebar, for stability and control
-"Soft touch" grips for a firm yet soft and pleasant grasp.


The saddle of the ST 100 is welded to prevent any movement of the saddle.
And because your comfort is our priority after your safety, we've added an exclusive wider Ergofit 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 saddle.


Two V-Brake pads for effective braking.
These brakes are composed of callipers 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 aluminium 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!
Because you're getting started with MTB touring on dry ground, this mountain bike is equipped with DRY 27.5 x 2.0 tyres. Great performance thanks to a central section with low rolling resistance and side knobs that provide good grip on turns.


The Rockrider ST 100 mountain bike is supplied with hard resin platform mountain bike pedals for added lightness and safety.
If your foot slides on the pedal, there's less risk of injury.


We added a quick release system for easily attaching/removing the front wheel.
There is a nut at the back to secure the bike and limit the risk of theft. You will need a spanner to remove the rear wheel.
Our advice: a bike rack is an easy way to transport your mountain bike without dirtying your car.


Your ST 100 mountain bike comes with a derailleur guard, chainwheel guard (to keep your clothes from getting dirty), bell, lights, wheel reflectors, and pedals.
The frame is compatible with:
- Front and rear mudguards (Flash MTB or MTB 700)
- Stand (500 Adult Base)
- Bottle cage
- Saddle bag
- Rear pannier rack
- Child seat (depending on the model)


Your bike's fittings (chain, derailleur, brakes, etc.) will adjust over time. Take advantage of a free servicing within 6 months after purchase. Our technicians will carry out a 13-point check of your bike. Just come to your nearest Decathlon workshop with your Decathlon card and/or receipt.


To ensure components last longer, we recommend a maximum load of 120 kg (rider and MTB included).


XS - 140-154cm: 15.3 kg
S - 155-164cm: 15.4 kg
M - 165-174cm: 15.5 kg
L - 175-184cm: 15.6 kg
XL - 185-200cm: 15.8 kg
Weight without pedals.

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How has this product been built

Composition / advice

Frame (for bike)
100.00% Aluminium
Stock advice After washing, rub with a dry cloth to remove all traces of moisture. Store your mountain bike in a cool, dry place, away from corrosive products and salty air.
Restricted use : Not suitable for XC, All Mountain, Enduro and BMX.
instructions To get more information about this product, please read instructions
Legal notice To ensure components last longer, we recommend a maximum load of 120 kg (rider and MTB included).

Our commitments

Test Product Our engineers always have real riders test all our products in real conditions. These tests round out our lab tests and let us validate all our products before they hit store shelves.
Guarantee : Lifetime (frame, stem, handlebar). Availability of spare parts: 2 years.

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