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ROCKRIDER ST 900 Women's Mountain Bike - 27.5"

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was £549.99 -%


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£549.99 -%
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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The women's ST 900 is a great hardtail mountain bike designed with the trail rider in mind. This machine focuses on comfort and control. At it's heart it an exclusive lifetime warranty double butted 6061 alloy frame weighing only 1.6kg. It features double walled 27.5" rims and smooth running sealed bearing hubs, lockable 120mm travel Rockshox 30 Silver front forks, modern 1x11 gearing and tektro designed hydraulic disc brakes. The wider bars, ladies hammock saddle and 2.2 wide tyres complete this fine package.

Also available in unisex versions.
Available in 3 sizes: S, M and L
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

Anatomic design Comfort for women: saddle, adjustable fork, raised position, closer brakes
Efficiency Smooth riding: lighter wheels, single chainring and fork lockout.
Directional control Hydraulic brakes and fork, and 2.2 all-condition tyres
Ease of use Change speeds, lock your fork, or adjust the saddle, in a single step.
Lifetime warranty Rockrider provides a lifetime warranty on the frame, stem and handlebar.

Technical Information


This women's ST 900 mountain bike is available in several sizes:
S: between 1.50m and 1.64m
M: between 1.65m and 1.74m
L: between 1.75 m and 1.84 m
If you are between 2 sizes:
Choose the smaller size for easier steering (easier to handle) and comfort (straighter back).
Choose the larger size for easier pedalling with a more stretched-out position (position more suited to performance).


The women on our mountain bike team helped design the ST 900 mountain bike to specifically take into account women's bodies:
The ergonomic saddle is hollowed out in the centre for improved comfort.
The fork is adjustable from 45 kg for more flexible suspension and greater enjoyment when riding.
The handlebar is narrower to better fit women's shoulders.
The brake levers are closer for an easier grip.
Shorter 60 mm stem for a better riding position


We created this ST 900 mountain bike at our B'Twin Village (Lille, France) especially for mountain biking enthusiasts. A comfortable, efficient mountain bike: ROCKSHOX 120 mm fork to overcome obstacles easily and remote lockout, single chainring and 27.5" light double-walled wheels for greater efficiency.
Women riders have been involved in every stage of designing the ST 900 Mountain Bike.


For less weight and more efficient pedalling, the Rockrider ST 900 frame has been designed with 6061 aluminium (only 1.6 kg in size M). It is 300g lighter than the ST 540 frame thanks to its double butted front triangle.
Our designers have designed and developed it so it is comfortable and easy to manoeuvre. Its slope has been designed to keep your back straighter. The lower bottom bracket helps keep you more stable during turns.


The 120 mm Rockshox 30 Silver hydraulic fork is 400g lighter than that on the ST 540 MTB. It is conical and offers even more stiffness and precision when steering.
It can be adjusted to the rider's weight using a conversion chart.
Adjust the fork's hardness and rebound easily (using a conversion chart).
The fork lockout on the handlebar (COMBO LOCK) helps prevent bobbing and loss of speed on flatter terrain.


The single chainring is easy and efficient to use.
1 chainring and 11 speeds: accelerate on the flat and take on climbs with no compromise.
1 single shifter on the handlebar: adapt your speed instantly like the pros as the terrain changes!
In detail:
-SRAM X1 32-tooth single chainring
-MICROSHIFT M665 11-speed rear derailleur
-MICROSHIFT M8515 right shifter
-MICROSHIFT H113 11-cog 11 to 46 teeth cassette
-KMC X11 chain


The adjustable stem brings the ST 900 controls to your hands.
The all-aluminium ROCKRIDER 60 mm stem (size S/M/L) and can be raised using 5 adjustment intervals.
In detail:
-620 mm wide aluminium handlebar
-ROCKRIDER ERGONOMIC grips for good grip and a comfortable feel
-The brake levers are 1 cm closer since women's hands are generally smaller Easy braking thanks to a more comfortable position.


Our team created and designed the Rockrider "Women Comfort Sport" ergonomic saddle especially for women.
It fits the shape of the female pelvis, and has a hammock shape. It is hollowed out in the centre and profiled to prevent chaffing while on mountain bike rides lasting 3 hours or more.
The Flex 27.2mm diameter aluminium seatpost also contributes to its increased level of comfort.
Quick and easy tool-free adjustment of your saddle height using the adjustment lever on the seat post clamp.


No matter what conditions you ride in (dry/wet), the Rockrider by Tektro hydraulic disc brakes (180 mm at the front and 160 mm at the rear), will come through for you, even in the mud.
Hydraulic braking adds more power and progressive braking and requires less effort applied to the brake levers.
The aluminium brake levers are easy to grip, lightweight, and precise.


The 27.5" wheels are lightened with double walls. Their sleeved rims, combined with the lightened tyres, are 230g lighter than on the ST 540.
With their 28 spokes, they are lightweight, stiff, and durable.
The exclusive ROCKRIDER ALL CONDITIONS LIGHT 27.5"x2.2 tyres have side knobs for all terrains. A width of 2.2 means more grip on technical sections.
Tubeless Ready rims: you will need rim tape, specific valves and sealant.


Not all rides start on your doorstep. This is why we've made it easy to remove and attach the front and rear wheels. They are equipped with a tool-free quick-release system (fastening levers).
A bike carrier will make your life easier if you want to avoid dirtying your car.


On your first few rides, your Women's ST900 MTB's components (chain, derailleur, brakes, etc.) will shift a little as they adjust to your rides. We offer a free maintenance check in the 6 months following your purchase. Our technicians will carry out a 13-point inspection of your bike. Visit your nearest Decathlon workshop and our customer support website:


S - 150-164cm: 12.85 kg
M - 165-174cm: 12.95 kg
L - 175-184cm: 13 kg
Weight without pedals.

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Composition / advice

100.00% Aluminium 6061
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.
Legal notice Your bike's weight may vary due to tolerances in the components. To make your wheels last longer, we recommend not exceeding the maximum weight of 120kg (rider with mountain bike).

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.


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 900 Women's Mountain Bike - 27.5
Maintenance and repair
Maintenance and repair
ST 900 Women's Mountain Bike - 27.5"
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