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ROCKRIDER ST 100 Women's Mountain Bike, White - 27.5"

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was £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, women's 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

Due to high demand, we are currently suspending online delivery for bikes. We are now increasing the availability of our bikes in our store showrooms while continuing with our Click and Collect service. This is a temporary measure and we thank you for your patience and understanding.

Product benefits

User comfort Comfort for women: ergonomic saddle and fork adjustable starting at 45kg.
Durability An ultra-strong MTB: double-walled rims, welded saddle, derailleur guard.
Efficiency Fly with a light frame, 21 speeds, 27.5" (XS 26") wheels & fast rolling tyres.
Ease of use Change speeds quickly: grip shifters & closely-spaced brakes.
Lifetime warranty ROCKRIDER offers a lifetime warranty on the frame, handlebars and stem.

Technical Information

Which is the right size?

Here is our guide for MTB sizes.
XS:between 1.40m and 1.54m
S: between 1.55m and 1.64m
M: between 1.65 m and 1.74 m / 15.5 kg in size M
L: between 1.75m and 1.84m
To fit your MTB to your 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 the foot on the pedal in the lowest position.
3/ If you're between two sizes, choose the smaller size.


Designed and developed entirely in France at the B'Twin Village (Lille).
The team observed and studied women's needs and used this to design and test the ST 100 MTB, involving mountain bikers at every stage of the process.
Our aim is to make you want to jump onto your comfortable, easy-to-use mountain bike so that you enjoy every one of your rides.


We carried out studies:
These included studies with the Decathlon Sports Lab, and real-world tests with hard-core women mountain bikers.
The result: a bike with positioning elements designed for women!
These include:
- A comfortable saddle with a hollow centre that is adapted to wider hips.
- An adjustable fork based on your weight starting at 45kg.
- An XS frame starting at 1.40m


Because we've noticed that it's not always easy to get the right position on a mountain bike, our designers have created an entirely new frame that's easy to get onto.
The CGF frame (Comfort Geometry Frame) is 100% aluminium for optimal comfort and excellent manoeuvrability. The slope angle has been designed to keep your back straight, while the low rear ensures the bike is very agile in turns.


Adjust the suspension hardness based on your weight, from 55 to 80 kg, to get over roots and stones more easily. All thanks to the UFIT concept (exclusive to Decathlon).
Easy: simply turn the adjustment wheel!
The 80 mm front suspension is designed for slightly uneven trails and helps you overcome obstacles with peace of mind.
Its design, based on a mechanical spring, is reliable and easy to maintain.


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 pedalling.
In detail:
-Triple-chainring chainset (22/32/42 teeth)+ anti-grease protection.
-Microshift FD-M20 front derailleur
-Microshift RD-M25 rear derailleur
-Microshift MS25 grip shifters with speed indicators
-Shimano TZ500 7 cog cassette, 14 to 28 teeth
-Large, solid KMC Z51 chain


The 90mm long aluminium stem, with a 10° angle, provides maximum comfort!
- The 620mm-wide steel handlebar provides stability and control.
- The soft touch handles are comfortable to hold and provide good grip.


The 2 V-brakes are made of 2 callipers that exert pressure on the rim to slow or stop the rotation of the wheels.
The brakes can be applied using only two fingers.
One a year, check how the pads are wearing.
If the grooves are disappearing, take your bike to your local store's workshop.
We offer a free inspection of your mountain bike within 6 months following the purchase of your bike.


Take on your first obstacles! The wheels are effective and sturdy: 27.5", double-walled rims, 28 spokes (26", single-walled and 32 spokes in XS). The rim is lined for added durability and shock absorption. The DRY 27.5 x 2.0 tyres offer optimal performance with a rolling central part and knobs on the side to grip the ground on corners.


The Rockrider ST100 mountain bike comes with resin platform mountain bike pedals for added light weight and safety. If your foot slips off the pedal, there's less risk of bruising your shin.


Not all rides start on your doorstep.
Need to remove the front wheel?
It's easy thanks to the clamping lever built into the wheel.
And the rear wheel?
There is a nut at the back wheel to secure the bike and reduce the risk of theft.
Note that a flat spanner is needed to remove the rear wheel. For safe rides, don't forget to bring anti-puncture spray.
To keep your car clean, a bike rack can make your life easier.


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.
Other optional available accessories:
-Front and rear mudguards (Flash MTB or 700 MTB)
-Stand (500 Adult Base)
-Bottle cage
-Saddle bag
-Rear pannier rack
-Child seat (Polisport Groovy, frame mounted)
-Gel seat cover
All item codes can be found on our website


The saddle of the ST 100 is welded to prevent any movement of the saddle.
We recommend that beginners wear cropped bottoms or cycling shorts with a pad (foam in the shape of a saddle) or a gel saddle cover to reduce soreness. For long rides, it's always a good idea to take a drink with you (e.g. a hydration bladder or bottle) and a helmet.

An easy-to-understand MTB with stickers

Did you notice the coloured stickers over your mountain bike?
Don't worry, it's not to add a touch of colour.
Resistant to wear, they provide hints on how to adjust your bike:
-adjusting the fork
-tyre pressure
-rim diameter
-saddle height
When you head out on a ride, it's useful to have the manual directly on your mountain bike!
For other information (washing, chain maintenance, etc.), please refer to our bike care guide.


To get the most from your mountain bike, you can equip it with:
a pannier rack / model 500 onesec / ref 8364376
a kickstand / model kickstand 500 / ref 1824001
and a mudguard kit / ref 8385291


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

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 Your bike's exact weight may vary due to the components' tolerances.
The total weight (bike + rider) should not exceed 120kg.

Our commitments

Test Product Our team did real-world tests in the field to test our bikes with women mountain bikers. These tests are in addition to our lab tests, and allow us to validate all our products before they are put on the market.
Guarantee : Lifetime (frame, stem, handlebar). Availability of spare parts: 2 years.


Q : How to assemble your bike?
Everything you need to know about making sure your bike is comfortable, secure and ready to ride.
Q : How do you adjust your brakes?
Having properly functioning brakes is vital when out on the road. Check out how to get them working to your liking.
Q : How to replace a brake lever on a bike?
Having properly functioning brakes is vital when out on the road. Here’s a video to show you how to make sure your new brake level is working nicely.
Q : How to replace a disc brake?
Having issues with your disc brake? Then this video is for you.
Q : How to adjust your bike handlebar?
A suitable handlebar height is essential to your cycling safety and comfort. Find out how to adjust it to your liking with our video.
Q : Do you offer a Cycle To Work scheme?
Find out everything you need to know about way of getting to work that’s good you and the environment.Check Here

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ST 100 Women's Mountain Bike, White - 27.5
Maintenance and repair
Maintenance and repair
ST 100 Women's Mountain Bike, White - 27.5"
Because you look after your own health, we look after that of your products: tips for initial settings, maintenance and repair advice, video tutorials, FAQs, instructions...
See our tips Spare parts