REF: 8615848


This 29" mountain bike is designed for all year round mountain bike tours, from 2h to 3h.

Comfort and reactivity to the hazards of the terrain: the 29" wheels (27.5" in S), the single chainring and the hydraulic disc brakes of the EXPL 500 mountain bike will change your mountain bike rides!

First use

Inflating your tyres

The recommended average tyre pressure is 1.8 bar.

If you're looking for more comfort and grip AND/OR if you weigh under 70kg, you can reduce the pressure by 10% but without dropping below 1.6 bar (the minimum recommended pressure). On abrasive terrain, however, this will increase the risk of punctures.

You should check the pressure of your tyres regularly.


Adjusting the height of your handlebars

Your handlebar is set to the most raised position, which is the most comfortable position for riding.

For improved aerodynamics and more efficient pedalling, you can lower your handlebar so that your body leans forward and adopts a more racing-like position.

Follow the steps in this video to move the headset spacers below the stem and lower the handlebars on your bike.


Aligning your handlebar

Check out this video to learn how to align your handlebars.


Positioning your brake levers

Check out this video to learn how to orient your brake levers.


Adjusting the height of your saddle

Your bike frame is fitted with a quick-release lever.

Stand next to your saddle. Tilt the quick-release lever to unlock it. Pull the saddle up or push it down to bring it level with your pelvis.

Tilt the lever again to lock it.

To make sure you get it right, take a look at our tutorial video.


Adjusting the tilt of your saddle

Check out this video to learn how to adjust the tilt of your saddle.


Adjusting the stiffness of your fork

The BTWIN U-Fit fork has been designed to be as easy as possible to adjust.
It features a real innovation: turn the dial until your weight appears on the top of your fork. 
As you turn the dial, the spring will be compressed or released to adjust it to your weight.

Changing your pedals

Check out this video to learn how to replace your pedals.


Bedding in your brakes

When you first get your bike from the store, the brake pads and discs are brand new and therefore the initial braking performance is very low (weak). A sharp prolonged braking action (for example, during a descent) with brakes that have never before been used can cause the pads to overheat and to "freeze up".

To ensure that your brakes perform well, we recommend you bed them in. This takes about 10 braking actions per brake. For each braking action: apply a single brake to slow the bike down from about 25 km/h to 5 km/h, without fully blocking the wheel. Repeat with the other brake.

How to convert your wheels to tubeless

To reduce the risk of your inner tube being punctured or pinched, you may want to consider making the wheels on your MTB "Tubeless".

To do this, you will need to buy:

- A pair of TUBELESS tyres:
- 21mm rim tape:
-A pair of Schrader TUBELESS valves:
- Sealant (anti-puncture):

1. Remove the wheel
2. Remove the tyre and inner tube from the wheel
3. Apply rim tape (sealant tape) to the rim
4. Insert a Schrader Tubeless valve through the rim hole (from inside the rim)
5. Apply tyre sealant (puncture prevention) liquid
6. Install your new Tubeless tyre
7. Fully inflate the tyre until it presses firmly against the rim
If you find it difficult to perform this operation, please visit your nearest Decathlon workshop and have this done for you.


The right equipment in case of a hiccup

Don't forget to take the essentials with you in the event of a flat tyre, broken chain or other mishap while mountain biking.
Following are some products that can be of great help should you encounter a mechanical misadventure.

Have a problem?

A wheel is bent

When you take your new bike out for a ride for the first time, a lot of parts can shift and fall into place.
You'll hear the spokes on your wheels creak because of the residual torsion in them.
Your bike is equipped with sturdy double-walled rims (on the inside of the wheel), so your wheels should be straight and not bent.
In the unlikely event a wheel is or becomes slightly bent or twisted, please bring your bike to any Decathlon workshop and they will make the adjustment free of charge, either:

1- As part of the free tune-up available within 6 months of the date of purchase of the bike.

2- If you've purchased our €1 breakdown insurance, under that policy (valid for 2 years)

Message for parents: Some technical moves performed by young riders (wheelies, skids, jumping etc.) can result in play in the rear hub or warping of the wheels if performed too often.If your child performs these tricks on a regular basis, speak to them and let them know the problems they can cause.

wheelies and buckling of the ROCKRIDER ST 100 mountain bike's wheels
Repairing a flat

Unfortunately, a flat tyre is something that can happen to any of us.

The terrain (thorns, brambles, glass, nails, etc.),

or the way the bike is used (jumping over obstacles such as rocks, steps, kerbs, potholes, etc.), are the most common causes, respectively, of flat tyres due to a puncture (small hole) or pinching (small grooves close together). However, if you keep getting punctures, it might be because of:

- The bike was improperly assembled at the factory, leaving the tip of one of the spokes exposed, which is puncturing the inner tube.

- The tyre or the inner tube is faulty (porous)

- A previous puncture was improperly repaired and a foreign object (thorn, bit of glass, metal shard, etc.) got into the rim or the tyre.

It's important to properly diagnose the flat and make sure the tyre and wheel rim are free from any foreign objects before doing the repair.

Not sure how to remove/fit a tyre, or how 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 sealant tube onto the valve of the flat tyre (valve should be in the lower position) and squeeze and hold to inject the foam into the inner tube. The tyre should become full and firm once more, allowing you to get back home safely.

2- If you've purchased our €1 breakdown insurance, you can have your tyre repaired at any Decathlon workshop.

3- To repair or replace the inner tube yourself, please refer to one of the video tutorials which you'll find below.

Rockrider ST 100 MTB Tyre Puncture
Your fork is too stiff

There are a couple of things you can do to "soften" your fork:

1. Adjust the stiffness: check the "ADJUSTING THE STIFFNESS OF YOUR FORK" section

2. Do some basic maintenance: you can regularly care for your fork with a small oil can. Simply put a few drops of oil on the fork pivots and work the fork to help the oil penetrate into the blades.

3. Have the bike fully serviced in a workshop.

Rear gears don't shift properly

There are several things you can do to ensure your rear gears shift properly:

1. Check the cable and its housing ends:
1a. Housing ends that are out of position can obstruct the derailleur cable when it is being pulled and prevent the gears from shifting smoothly. If a housing end is out of position, push it back into place.

1b. 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 housing replaced.

You can opt to replace them yourself by watching this video, or bringing your mountain bike to a Decathlon workshop.

2. Check that the derailleur dropout isn't bent:
A bent hanger causes the derailleur to be out of alignment and therefore unable to function correctly. Stand behind your bike and check the alignment of the derailleur.
If the hanger is bent or broken, please visit your nearest Decathlon workshop to have the derailleur hanger replaced. You can also replace it yourself by following the instructions in this video tutorial in the "BROKEN HANGER" section

REMEMBER: You can have all the settings on your bike checked for free in the first six months following the date of purchase.

NB: If you regularly ride your MTB in wet or muddy conditions, or if you regularly wash your bike with lots of water, then your cables and cable housing will need to be replaced more frequently. Washing your bike using a high pressure hose is highly discouraged as it can push dirt and dust into the cable housing.


The brake lever touches the handlebar too easily before braking starts

If your brake lever feels spongy and/or touches the handlebar before your bike starts to slow down: You need to bleed the brake system.

Visit one of our Decathlon workshops to get our technicians to do this for you.

Your derailleur hanger is bent

A bent hanger causes the derailleur to be out of alignment and therefore unable to function correctly.

Stand behind the bike and check the alignment of the derailleur.If the hanger is bent or broken, please visit your nearest Decathlon workshop to have the derailleur hanger replaced. You can also replace it yourself by following the instructions in this video tutorial.


Your chain has broken

Did your chain break? You have two options:

1- You can repair it yourself using our video tutorial. You'll need a quick-link and a chain tool. 

2- Visit a Decathlon workshop to have the operation done by one of our technicians.


Maintaining your mountain bike

Cleaning your mtb

To clean your bike properly, you'll need some bike cleaner, a sponge, and a brush.

Rinse off the bike with a hose and apply the bike cleaner.

Next, use the sponge and brush to apply the cleaner effectively.

It's essential to give the bike cleaner some time to act before rinsing the bike off.

When hosing the bike off, make sure you do so from a few steps away so as not to damage the mechanical components.

Lastly, dry your bike using a cloth that is dry, clean and soft.


Cleaning and lubricating your drivetrain

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.

Next, spray the degreasing agent onto the entire drivetrain, scrub the cassette, the chain, and the rollers on the derailleur with the brush.

Let it sit for a few minutes before rinsing with a hose from a moderate distance.

Wait a little while to let the drive train dry before moving on to the greasing step.

For greater effectiveness, shake the can of bike lubricant and spray on the inner side of the chain.


Replacing a drivetrain cable

Is your drive train cable dirty, rusty, damaged, or do you find changing speeds to be difficult or unreliable? 

If so, you need to replace your drive train cable. To do so you'll need a pair of pliers, a screwdriver, a wirecutter, an Allen key, and a new set of derailleur cables and cable housing.

First, remove the cable from its 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.

Install the cable on the shifter and pull it through the housing. Once done, put the cover back on the shifter and attach the cable to the derailleur. To adjust the drive train, tighten the cable if you have a hard time shifting to higher gears, and loosen it if you have a hard time shifting to lower gears.

Once adjusted, cut the cable and put a cap on the extremity using a pair of pliers.


Removing your rear wheel

Check out this video to learn how to remove your rear wheel.


Repairing a flat tyre

To repair a flat tyre, you will need: a bicycle pump, a basin with water, a dry cloth, and an inner tube repair kit.

Partially inflate the inner tube. Submerge the inner tube into the water to locate the puncture by the source of the bubbles.

Once you have located the puncture hole, dry off the inner tube with the cloth and rub the spot to be repaired using the sandpaper included in the inner tube repair kit.

This prepares the inner tube for glueing and ensures that the patch sticks to the inner tube as securely as possible.

Generously apply glue to the inner tube around the hole and wait 3 to 5 minutes.

Then apply the patch to the hole and hold it in place for a few minutes.

You can then fit your inner tube back into the tyre.


Replacing the brake pads on mechanical disc brakes

To do this, you will need: brake pads, a flat head screwdriver, and a 3 mm Allen key.

First, remove the wheel. Next, use a large flat head screwdriver to separate and remove the pads, and put the pistons back into their original position.

Next, remove the pin that holds the pads, and remove the pads from their casing. Prepare the new brake pads by placing the return spring between them.

Insert the new pads in the brake calliper and then put the pin back in place to complete the process.

Put the wheel back on and do a visual inspection to check that the brake pads are in their proper place and do not rub against the disc.


Adjusting the mechanical disc calliper

For this operation you will need a 5 mm Allen key.

Unscrew the brake calliper, spin the wheel and operate the brake lever. It is important to keep the brake lever engaged before screwing the calliper back in place. 

Check to see that the disc and the pads are still in contact. 


Replacing your derailleur hanger

To do this, you'll need a new derailleur hanger that's compatible with your bike (please check our "SPARE PARTS") and a 5 mm Allen key.

Remove the bike wheel as well as the damaged derailleur hanger using suitable tools.

Position the new hanger on the frame.

Remove the old hanger from the derailleur before installing the new hanger using the 5 mm Allen key.

Then install the derailleur onto the new hanger and check that you can change gears properly.


Replacing the chain

To do this, you will need: a chain tool, a new chain, and a quick-link.

Put the chain on the cog and on the smallest chainring. 

Remove the quick-release link using the 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 chainring. This makes it easier to determine its optimal length.

Pull the chain down, pass it under the upper pulley of the derailleur.

Once you've defined the correct length, use the chain tool to cut the chain.

Lastly, install the quick-link onto the chain, turn the pedal so as to position the quick-link on the upper part of the chain, and use your hand to apply pressure and ensure it is firmly locked in place.


Compatible accessories

Mountain bike mudguard kit

Fit the MOUNTAIN BIKE MUDGUARD KIT on your EXPL 540 mountain bike

mountain bike mudguard kit
500 Base stand

Fit the 500 CHAINSTAY STAND to your EXPL 540 mountain bike

Side access bike bottle cage

Fit the SIDE ACCESS BIKE BOTTLE CAGE to your EXPL 540 mountain bike in order to set 2 bottles
If you only want one bottle, you can chousse a bottle cage with front access


Spare parts

Need to replace a part on your bike? You'll find all our spare parts for the EXPL 500 MOUNTAIN BIKE right here.


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

User guides


Need instructions for your EXPL 540 mountain bike? 


Need instructions for your brakes?

User guides

Need instructions for your drive train? 


Our commitments

Rockrider provides a lifetime warranty on your MTB's frame, handlebar and stem (under normal conditions of use).

All other parts have a 2-year warranty.

When you start riding your bike, some components will move slightly. This is why we offer a free tune-up of your mountain bike within six months of purchase.