REF: 8405170



We have designed this mountain bike for children aged nine to 12 (135 to 150cm) who want to perfect their mountain biking skills.

Thanks to its aluminium frame, it is lighter and more versatile when it comes to taking on obstacles. With its suspension fork and disc brakes, there is nowhere it cannot go.


Brake barrel adjusters

There are two barrel adjusters on each brake, situated on the brake levers. They are used to adjust the tension of the brake cable. Make sure you get the setting right when using the barrel adjuster. (The more the barrel is tightened, the tighter the cable).

Derailleur barrel adjuster

This barrel adjuster is located to the rear of the derailleur. It is used to adjust the tension of the derailleur cable. If the chain struggles on climbs, it means the cable is not tight enough. Tighten it by unscrewing the barrel. If the chain does not run smoothly on descents, then the cable is too tight. Turn the barrel to slacken the cable. A quarter turn is often all you need.

Disc brakes

This mountain bike is fitted with front and rear mechanical disc brakes, guaranteeing powerful braking in all conditions.

Stem bolt screws

The two screws secure the stem to the head tube on the fork.


First use

Adjusting the height of the saddle before your first ride

It's important to adjust the height of the seat tube and the handlebar to fit your child's height. The mark indicating the minimum insertion point of the seat tube, or the handlebar, into the frame, should never be visible for safety reasons (make sure that neither the seat post nor the handlebar extend past this minimum insertion level).

To determine the correct seat height: sit your child on the bike with one heel resting on the pedal with the crank turned so that the pedal is at its lowest position. The seat height is correct when the child's leg is extended while in this position. Also while seated, check that the child can touch the ground with their toes.

What is the recommended pressure for 24" mountain bike tyres?

The recommended pressure is always indicated on the tyre sidewall. We recommend inflating your tyres to the pressure indicated on each tyre, This may vary from tyre to tyre. 

You can check that your tyres have enough air in them simply by putting your child in the saddle. With their weight, the tyre should go down ever so slightly. 


Compatible accessories

1. Front and rear mudguards
2. The stand
Fitting the stand
3. The bottle cage: fitting one on a mountain bike


Maintaining your 24" mountain bike

Lubricating the chain on a children's mountain bike

You can use an "all-in-one" type product (available at Decathlon stores) to unjam, clean, lubricate and protect your child's bike. It's a very handy product! To lubricate the chain, turn the pedal and "spray" the product all the way along.  Then leave it to dry for a few minutes. If the chain is very dirty, clean it with a brush or a cloth and spray it again with "all-in-one" product.   Our tip: Avoid any contact with the brake pads and the braking area on the wheel rims.   Protect your bike: Apply all-in-one regularly to prevent rust from appearing.


Washing your child's mountain bike

If you notice that your child's bike is dirty after a few rides (mud, rain, dust, etc.), it's a good idea to take a few minutes to get it clean again as needed.   If it's covered in dust, just use a dry cloth to clean it. If there's mud or other dirt that's harder to get rid of, you can clean it with a bucket of hot water, a sponge (or a cloth) and some bike wash or shampoo. You can clean parts such as the frame, fork, handlebars and wheels).   DID YOU KNOW?   We strongly recommend that you do not use a pressure hose to clean your child's bike: It may damage the functions of components such as the headset and the bottom bracket and put your child in danger.    When you've finished washing the bike all you have to do is wipe it down with a dry cloth to prevent rust from appearing. You might want to apply fresh lubricant to the moving parts (chain, headset, bottom bracket). 

How to check the condition of your tyres

You should always check the tyres before you take your bike out.  If they're flat, check to see if they have a puncture. To do this, blow them up as much as you can. If they go flat quickly, you will have to take the wheel off and then the tyre and change or repair the inner tube.  If they go flat slowly, check the surface of the tyre for the presence of sharp objects or shards of glass. You will then need to take the wheel off and then the tyre and change or repair the inner tube. Take care when removing the sharp object or shard of glass causing the puncture.    Even if they're not flat, we recommend you check the pressure of the tyres (see section above).    DID YOU KNOW? The useful life of rubber depends on how it is used and stored. If you can see cracks in the tyres, we advise you to replace them with new ones. 

How to store your bike

We recommend you keep your bike in a dry place.  You should check that it doesn't get damp. The lifespan of your child's bike depends on how it is used, maintained and stored. The more damp and saline (sea air) the conditions, the more the child's bike will be prone to corrosion and the shorter its useful life.   It's important, therefore, to keep it stored, clean and dry, in a place that is not damp.    DID YOU KNOW? You shouldn't hang up bikes with telescopic forks by the front wheel. Hang them up by the rear wheel. This will ensure your fork lasts longer. 

Checking disc brakes for wear 

If you find that your brakes are not quite as responsive as when you bought the bike, it might be time to change the pads.  As with car brake pads, the disc brake pads on bikes wear out and have to be changed.When checking the pads make sure there is more than a millimetre of braking material left on the brake pad. 

There is a problem

What to do if you have a puncture changing an inner tube

If you suffer a puncture, stop immediately in a safe place to prevent the rim from being damaged.  Turn the bike upside down and set it down on the ground on the saddle and handlebars. Release the brakes to allow the wheel to come out. Squeeze the V-brake callipers together and release the noodle.  For the front wheel, remove from the fork and then change the inner tube (see explanatory video).  For the rear wheel, position the derailleur on the smallest cog. Loosen the wheel and then change the inner tube (see explanatory video).    As a last resort, you can always use puncture repair spray though this won't work if the inner tube is torn.

Changing an inner tube on a child's mountain bike.

The gears are not shifting smoothly. what should be done?

If changing gears is a struggle, it's because the rear derailleur doesn't align properly with the cogs.    Check the cable and housings: If the housing ends are out of position they can obstruct the derailleur cable and stop the gears from changing. Simply slip them back into their housing. If the derailleur is not moving even after you have engaged and disengaged the grip shifter, it probably means that the cable and its housings have seized up. You will need to have the cable and housings replaced.   It's possible that the derailleur hanger has been bent or knocked out of shape. This makes it impossible to change gears. Our advice is to take the bike to the workshop at your nearest Decathlon store and have the hanger straightened.    It's also possible that the derailleur is not working properly. If that's the case, put the bike upside down on the saddle and handlebars and release the pedals (or preferably put it on a bike stand if you can). Activate the shifter/trigger (depending on your bike's configuration) to move the chain on to the smallest cog. The barrel adjuster is located to the rear of the derailleur. It is used to tighten and loosen the derailleur cable, respectively moving the derailleur up or down. Adjust the barrel until the gears shift correctly. 

The brake lever is touching the handlebars. what should be done?

If the brake lever is too slack, too limp or is touching the handlebar without much pressure being exerted on it, use the barrel on the brake lever to adjust the tension of the brake cable, as shown in the video below.   Unscrew the barrel and the locknut until the cable is sufficiently tight and the brake lever is firm but not too hard. Once you've got the tension right, tighten the locknut firmly against the brake lever to secure the setting. 

ROCKRIDER 24" 900 mountain bike red

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ROCKRIDER 24" 900 mountain bike red

Our btwin 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.