REF: 8405350


A bike specially designed for people who are new to cross-country mountain biking (XC). Excel yourself and break new ground on every ride.~With its NX Eagle drivetrain, Markhor fork and 29" wheels, our aluminium XC mountain bike is guaranteed to perform."

First use

Bedding in your brakes

The brake pads and discs on a new bike are new themselves and don't work to their full potential.Hard, continuous braking (on descents, for example) can cause the pads to overheat and "glaze".To prevent this from happening and to ensure that your brakes slow you down effectively, we recommend that you bed them in.You need to apply each brake firmly around ten times to bed them in properly. The bedding-in process involves getting up to a speed of 25 km/h and then applying just one of the brakes firmly to reduce your speed to 5 km/h, without locking the wheel.

How to convert your wheels to tubeless

You can avoid the risk of the inner tubes on your mountain bike getting punctured or pinched by switching to TUBELESS. To do this you'll need to buy the following: -Sealant: DECATHLON: TUBELESS READY TYRE AND WHEEL SEALANT (8550735)   STEPS TO FOLLOW:1. Take the wheel off.2. Remove the tyre and the inner tube from the wheel.3. Apply the tubeless rim tape.4. Insert a Schrader TUBELESS valve in the valve hole in the wheel.5. Apply the sealant.6. Fit your new TUBELESS tyre.7. You need to inflate the wheel quickly to ensure that the tyre sticks to the rim. If it seems too tricky, just visit your nearest DECATHLON workshop and ask them to do it for you.


Adjusting your fork

Click on the link below for MANITOU's instructions on how to adjust your fork.


Getting the right gear to deal with problems

You need to have the right equipment with you when you're out and about on your mountain bike so that you can take care of a puncture, a broken chain or any other type of setback.Here's a selection of products that can get you out of a tight spot or two. 

Have a problem?

The wheel is buckled

When you take your new bike out for a ride for the first time, a lot of parts move around and fall into place.You'll hear the spokes on your wheels creak because of the residual torsion in them.Your bike is fitted with double-walled rims, which help make the wheels more solid. That means they should not buckle in any way at all.If they do, then call in at one of our DECATHLON workshops to have them repaired free of charge:1. As part of a free check-up in the first six months following the date of purchase. 2. As part of our 1-euro damage insurance plan € (valid for two years).

wheeling and buckling wheels on a ROCKRIDER ST 100 mountain bike
You've got a puncture

It's a sad fact of cycling that everyone gets punctures. - The terrain (thorns, bramble bushes, glass, nails, etc)- and use of the bike (catching tyres on obstacles such as stones, steps, kerbs and potholes)are the most common causes of punctures and pinched tyres respectively.If you keep suffering punctures, there can be several factors at play:- The wheel has not been assembled properly in the factory and a spoke keeps piercing the inner tube.- A substandard tyre or inner tube.- A badly repaired puncture or a foreign body (thorn, piece of glass, shard of metal, etc) stuck on the rim or in the tyre.It's important to find out what is causing the puncture and to remove any foreign bodies before repairing it.I don't know how to put a tyre on or take one off so how am I going to repair or change an inner tube?1. The simplest thing to do is not to touch your wheel and use a can of puncture repair foam as a temporary solution: Screw the end of the tube on to the valve of the punctured tyre (with the valve pointing down) and press down to inject the foam. The tyre will regain its shape and hardness, allowing you to get home. 2. If you've taken out our 1-euro damage insurance plan, you can have your tyre fixed at one of our DECATHLON workshops. 3. If you want to repair or change the inner tube yourself, then check out the tutorial videos below.  

Puncture ROCKRIDER ST 100 mountain bike
The fork is too hard

There are one or two things you can do to make your fork "softer": 1. Do some basic maintenance: using a simple oil can. Squirt some oil on the pivots of the fork and move it around to work the oil into the blades.2. Have the bike fully serviced in a workshop.

The rear gears are not shifting properly

There could be several reasons why your gears (cogs) are not shifting correctly.1. Check the position of the housing ends.Housing ends that are out of position can obstruct the derailleur cable when it is being pulled and prevent the rear gears (cogs) from shifting smoothly. If a housing end is out of position, push it back into place.2. The cable and housings may have jammed up.If the smallest gears (cogs) do not move down, if the derailleur doesn't move even when the gear shifter is operated, then the cable and the housings have jammed up. They need to be replaced.3. Take your mountain bike to a DECATHLON workshop to have the derailleur adjusted. 4. Use the SRAM DERAILLEUR ADJUSTER to set your Sram derailleur to the correct position. This valuable tool adjusts the distance between the top pulley and the cassette. 5. You should also check that the derailleur dropout is not twisted. If it is, check the section "THE DERAILLEUR DROPOUT IS BROKEN"   NB: If you regularly use your mountain bike in wet or muddy conditions or if you wash it a lot, then you will need to replace the housings and cables more often.We strongly advise you not to use a pressure hose to wash your mountain bike as it will force dirt into the housings.


You start pulling the brake lever and it touches the handlebars

The lever is spongy and/or touches the handlebars before you can brake:You need to bleed the brake system.Drop in at a DECATHLON workshop and get one of our technicians to do it.

The derailleur dropout is broken

A twisted dropout causes the derailleur to become misaligned, preventing it from doing its job correctly. Look at your bike from behind and check to see if the derailleur is straight.If the dropout is twisted or broken, take your bike to a DECATHLON workshop to have it replaced. Alternatively, watch this video. It will show you how to replace it yourself.


The chain is broken

So you've broken your chain.You've got two options: 1. Repair it yourself with the help of this video. You'll need a chain tool and a quick-release link.  2. Drop in at one of our DECATHLON workshops and have it done by one of our technicians.


Maintaining your mountain bike

Cleaning your mountain bike

To clean your bike properly, you'll need some bike cleaner, a sponge and a brush. Spray the bike with a hose before applying the cleaning products. Use the sponge and brush to apply the products. Allow the product to act before rinsing the bike. Rinse it from a distance to avoid damaging mechanical parts. Finally, dry the bike with a soft, clean, dry cloth.

cleaning your mountain bike

Cleaning and lubricating the drive train

To clean and lubricate your drive train, you will need a degreaser spray, a soft bristled brush and a lubricant. The first step involves covering the brake disc with a clean cloth to prevent any lubricant from getting on to it. Then apply the degreaser to the whole of the drive train and scrub the cassette, chain and derailleur jockey wheels with the brush. Leave to act for a few minutes before rinsing the degreaser off from a suitable distance. Allow the drive train to dry before applying the lubricant. Shake the lubricant and apply to the inside of the chain, where it will work best. 


Changing a drive train cable

Is your drive train cable dirty, rusty or damaged or are your gear changes stiff, random or not as slick as they should be?  If so, the cable needs changing. You'll need a pair of pliers, a screwdriver, cable cutters, an Allen key and a new derailleur cables and housings kit. Start by removing the cable from the housing. Remove the hood from the gear shifter, move the indicator to the last gear and cut the cable. This will allow you to remove all of the cable and then the housing. Cut the housing to size and fit the end caps on the end of the cable, which is now ready to fit. Thread the cable through the shifter and push it through the housing. Then put the hood back on the shifter and attach the cable to the derailleur. To adjust the drive train, tighten the cable if the gears do not shift up easily and slacken it if they do not shift down smoothly. Finally, cut the cable and use the pliers to attach the end cap to it.


Taking off the rear wheel

Removing and fitting a wheel when your bike has a derailleur cage lock is a pretty tricky operation. Put the chain on the last cog and unlock the derailleur cage. To remove the wheel, just open the quick-release lock. To fit it back on, put the chain on the last cog, close the quick-release lock, and lock the derailleur cage to prevent the chain from jumping.


Repairing a puncture

You need the following to repair a puncture: a pump, a basin of water, a cloth and an inner tube kit. Put a little pressure on the inner tube. To find the puncture, submerge the inner tube in the basin of water. Once you've spotted it, dry the inner tube with a cloth and scrape the area around it with the sandpaper provided in the kit. Scraping the inner tube will allow the glue to adhere better. Apply the glue generously around the hole and wait for three to five minutes. Place the patch over the hole and hold it there for a few minutes. You can then fit your inner tube back into the tyre.   


Changing hydraulic disc brake pads

You will need the following: new brake pads, a flat screwdriver and a 3mm Allen key. Remove the wheel first of all. Then use the screwdriver to move the pads apart and put the pistons back into their original position. Take out the pin holding the pads in place and remove them from their housings.Position the counter spring between the new pads. Insert the new pads in the brake caliper and then put the pin back in place to complete the process. Put the wheel back on and check to make sure that the brake pads are properly in place and do not rub against the disc.


Adjusting the hydraulic disc caliper

You will need a 5mm Allen key. Unscrew the brake caliper, spin the wheel and operate the brake lever. It is important to keep the brake lever engaged before screwing the caliper back in place.  Check to see that the disc and the pads are still in contact. 


Changing the derailleur dropout

You will need a new derailleur dropout that fits your bike (check the "SPARE PARTS" section) and a 5mm Allen key. Take off the wheel and the damaged derailleur dropout. Position the new dropout on the frame.  Remove the old dropout part from the derailleur before fitting the new one with the Allen key. Fit the derailleur on to the new dropout and check the gears.


Changing a chain

You will need the following: a chain tool, a new chain and a quick-release link. Put the chain on the cog and on the smallest chainwheel.  Remove the quick-release link using quick-release chain tool and then remove the chain from the drive train. Put the new chain on the last of the cogs and on the smallest chainwheel. This makes it easier to determine its optimal length. The chain should pass close to the top pulley of the upper jockey wheel on the derailleur. Once you've determined the length of the chain, use the chain tool to cut it as required. Then fit the quick-release link on the chain and turn the pedal to position the quick-release lever on the top part of the chain. Press it with your hand to check that it is on the right position.



Spare parts

Need to replace a part on your bike? You'll find all our spare parts for the XC 100 mountain bike right here.

User guides


Instruction manual

Instruction Guide


Braking instructions


Suspension instructions

Drive train

Drive train instructions


Wheel instructions


Haven't been able to fix your problem or find what you need?

Please contact one of our technicians who will be happy to help


Our commitments

ROCKRIDER guarantees the frame, handlebar and stem of your mountain bike for life (in normal conditions of use).

The guarantee for other parts is two years.

As soon as your child starts using the bike, some components will move slightly. It's for that reason that we offer a free check of your mountain bike six months after purchase.