So, you’ve just got yourself a new mountain bike. Enthusiastic and motivated, the trails await. But just where do you begin the process of setting up your bike?

Mountain bike set up is crucial. A bike that’s not adjusted for your body size, preferences and discipline can result in the gradual accumulation of aches and pains that lead to eventual injuries.

To ensure maximum comfort and efficiency tailored to your geometry, let’s take a look at a few aspects of set up.
Saddle height and position

For efficient pedalling and the avoidance of knee pain further down the road, saddle height is of paramount importance.

At the ideal saddle height, you’ll want a slight 25-30° bend in your knee at the 6 o’clock position.

A saddle at the wrong height is usually noticeable and quickly remedied. However, it’s with saddle position where most people go wrong and run into trouble. Setting it too far forward or too far back can result in knee pain over time.

With your foot in the 3 o’clock position, align the front of the knee with the pedal axle. This is most easily achieved by having a friend gauge it from the side. Simply move the saddle forward or back until you achieve alignment.

In general you’ll want your saddle flat. Although for downhill, you may prefer it tilted slightly nose up to ensure it’s easier to slide off the back.

Suspension set up is always a compromise between a comfortable ride on rough terrain and efficient pedalling. It’s dependent upon several factors including the bike type, geometry, rider physique and of course, the trail you ride on.

Setting the sag

The first thing to set is the sag. The sag refers to how much the shock compresses when you sit on the bike. To set the sag, sit on and ensure all your weight is on the bike. It’s important to be fully kitted for this procedure, including your pack, as the extra weight will influence the setting. A good starting point for the rear shock is 30% sag.

The front fork can be set to slightly less. To set it, it’s best to roll on the flat with your shoulders above the handlebars pushing downward. Aim for 20-25% sag.

These configurations provide a good starting point. The geometry of the bike will distribute the weight differently in each case, and each shock can be later adjusted.


Additionally, your bike make have clickers on the suspension for compression and rebound damping. These provide the ultimate performance tweak. They control how fast the shock returns once engaged.

The type of riding you do will dictate the setting here. For rough, bumpy trails it’s best set for a slow response for a more in-control feel. However for flatter, smoother riding, a harder response is what is required. Experiment based on the nature of the trails you tackle.
Tyres and Pressure

Tyre types and threads

Whether it’s wet and slippery or dry and dusty, the weather conditions and trail conditions will affect tyre choice. At Decathlon, we provide an impressive array of tyres for all your mountain biking needs.

On a hard-packed surface, rolling resistance and grip are the most important factors. Here you’ll want to use a low-profile tyre with small rubber knobs that roll and grip well.

On softer, low-grip surfaces a tyre with protruding rubber knobs will bite into that softer surface and provide the much-needed grip.

For those hitting the singletracks on downhill trails, a heavier tyre is required. Here, grip reigns supreme and you’ll want a tyre with taller knobs to bite into the surface on the bends.

Tyre pressure

You’ll want to run your tyre pressure on the low side. To begin with, inflate them to the minimal pressure stated on the rim of the tyre. Decathlon provides a wide array of pumps with gauges which allow you to accurately inflate your tyres before each ride.

Trail conditions will dictate where you go from here. Trails which are rocky are best tackled  with a slightly higher tyre pressure, perhaps 2-3 PSI above minimum. While the bike will often run better on trails which are muddy and slippery on slightly lower pressures.

As most of your weight is centered over the rear wheel while riding, many riders find it useful to inflate the rear tyre slightly more than the front.

Additionally heavier riders may require more tyre pressure. For every 10 kg consider an extra 4-5 PSI in each wheel.
Handlebars, Brakes and Shifters

For supreme control and confidence, the positioning of the handlebars and levers should be adjusted based on your body dimensions and riding style. In the heat of competition or on technically challenging trails, you want to ensure optimal reaction time for maximal control.

Setting the handlebar height and angle

The first thing to set is the handlebar angle. Undo the stem bolts with an allen key and ensure the bars are centered. Roll them forward and back and experiment with different feels to find the sweet spot. If you feel cramped on the bike, roll them forward. Similarly, if you feel too stretched, roll them back.

Handlebar height can also be adjusted. Your bike should come with spacers which you can add or remove. Undo the cap on your stem and juggle them as necessary.

Higher handlebars are better for downhill riding as it keeps the weight further back. While for cross country, riding a lower setting tends to work better as it puts more weight on the front wheel.

Once tightened up, ensure there is no play in the stem as you jolt the bike forward while gripping the front brake.

Setting the brake levers

When breaking, ideally you shouldn’t have to adjust the position of your wrists. Moving them up or down to compensate for a misaligned brake lever results in a loss of stability. Likewise your fingers should not be over-extended when resting on the brake lever. The middle knuckles should wrap lightly around the lever.

The angle of the levers is dependent on discipline. In general it should be set slightly higher for downhill riding, and lower for climbing or when on the flat. The brake lever angle can be easily adjusted with an allen key.

Setting the shifters

Once the brake levers are correctly positioned you can set the shifters. By placing your hands in a natural position check to see if you can operate the shifters easily with your thumbs. Ensure you don’t set them too flat. When you’re sprinting out of the saddle, a slightly steeper angle of alignment can often help in quickly finding the gear you need. You’ll want to ensure that with one full stretch of the thumb that you can easily push the lever through.

In conclusion: With such variation in terrain, discipline, bike geometry, body types and personal preferences, setting up your mountain bike can take time. Once your bike is set up with a basic configuration, you can explore and tweak as you immerse yourself in this wonderful world. Just remember to bring along a multitool for those minor adjustments! At Decathlon, we stock a range of useful gadgets for those on-the-go tweaks!