What is the Head Angle on a Mountain Bike? (2024)

Have you ever ridden a mountain bike and felt like you were going to fall over? If so, it’s probably because the bike’s head angle was off. The correct head angle is key to ensuring your safety and a comfortable ride.

The head angle on a mountain bike is the angle in degrees between the ground and the bike’s head tube. The angle should be between 63° for slack and 73° for steep—with an average of 68°. Steeper head angles enhance stability at high speeds, while slack head angles allow more control descending.

In the rest of this article, I’ll discuss mountain bike head angle and how to measure and adjust it accordingly. I’ll also discuss the factors that determine the head angle on a mountain bike and how to know if you need to change it. Keep reading!

Mountain Bike Head Angle Explained

Head angle, also called head tube angle, is the angle at which the forks sit in relation to the horizontal distance between the rear and front axles.

You will locate this angle between the two bearings that make up the headset. The bottom bearing is called the crown race, while the top one is called the cups.

In most cases, frame manufacturers preset the head angle based on the bike’s intended use. For example, a cross-country bike will have a steeper head angle than an all-mountain or enduro bike because it needs to be more agile and lighter. However, adjusting the head angle is possible if you feel it makes riding challenging.

The video below illustrates the location of the head angle on a mountain bike:

Types of Head Angles on Mountain Bikes

Head angle is a crucial factor to consider when buying a mountain bike. According to Research Gate, the head angle affects saddle height, affecting your ability to control the bike.

There are two basic head angles on mountain bikes:

Steep
Slack.

Let’s take a deeper look at each of these head angles and how they affect riding and the bike’s stability.

Steep Head Angle

A steep head angle is one with higher head angle numbers in degrees ranging from 67° to 73°. Such an angle makes the bike more upright, an ideal posture for cross-country riding, where agility, speed, and lightness are vital factors.

A steeper head angle provides more stability at high speeds because the bike’s weight is evenly distributed between the front and rear wheels. This balance helps maintain control over the bike when going fast on flat terrain or downhill.

The angle also makes the front of your bike feel more planted to the ground. This stability makes it easier to navigate around turns by lowering the bicycle’s center of gravity (COG).

Pros of Steep Head Angle

It makes it easier to navigate corners with a tight turning radius along rough terrains.
It provides a better response even at fast handling speeds.
It makes ascending more efficient.
The rider has a better view of the trail ahead.

Cons of Steep Head Angle

It may feel twitchy and unstable at high speeds.
It is not efficient at absorbing shock, especially on bumps.
The bike feels scary for beginners due to its shaky nature.

Slack Head Angle

A slack head angle has lower numbers in degrees ranging from 63° to 66°. This angle makes the bike more laid-back, ideal for all-mountain and enduro riding, where descending is key.

A slack head angle provides more control when going slow or descending because your weight is shifted back on the bike. Riding a mountain bike with a slack head angle makes it easy to maintain control when going slow on flat terrain or downhill.

A slack head angle moves the front wheel further away. This angle creates more space between you and the handlebars, making it easier to absorb shock on bumps.

Pros of Slack Head Angle

It provides more stability and control at slow speeds.
It is more efficient at absorbing shock on bumps due to the extended fork.
The bike is less twitchy and more stable overall due to the increased wheel space.
It offers better cornering even at high speeds.
The relaxed posture boosts confidence even when riding downhill

Cons of Slack Head Angle

Not effective at navigating tight corners as the front wheel can flop.
The bike feels heavy and less nimble.
Climbing can be more challenging due to the extended fork that relays less weight on the front wheel.

Based on these descriptions, mountain bikes come in the following head angles:

Downhill mountain bikes: 60° to 65° head angle.
Trail mountain bikes: 65° to 68° head angle.
XC mountain bikes: 69°+ head angle.

How To Measure a Mountain Bike’s Head Angle

Measuring your mountain bike’s head angle allows you to know if the bike is slacked or steep. This measurement will enable you to go for the best angle, depending on where you’ll be riding.

You’ll need the following to measure your bike’s head tube angle manually:

A protractor
A tape measure
A long level of at least 24 inches(60cm).

Procedure

Start by finding the center of the head tube. You can do this by measuring from the top of the head tube to the bottom and dividing that number by two. Mark this point on the head tube with a pencil.
Measure the distance from the center of the head tube to the ground.
Place your long level on top of the headset. One end should touch the ground while the other extends out in front of the head tube. Make sure the level is perfectly straight.
Measure the angle between the ground and the long level using your protractor. This measurement is your bike’s head angle.

The following are other easier ways to measure your bike’s head angle:

Using Mobile Apps

Smartphone technology has made it possible to measure a mountain bike’s head angle using apps. All you need is your phone and the app, and you can get accurate measurements of your bike’s head angle within seconds.

Some of the best mountain bike head angle measurement apps include:

Bubble level
Smart Tools app
iHandy Carpenter app.

Using a Head Angle Gauge

A head angle gauge is a tool specifically designed to measure the head angle of a mountain bike. It’s a simple tool that you can use to get accurate measurements of your bike’s head angle.

The following procedure will help you use a head angle gauge correctly:

Loosen the bolts on the headset so you can rotate the fork.
Place the head angle gauge on top of the headset, ensuring it’s level.
Tighten the bolts on the headset to secure the gauge in place.
Rotate the handlebars until they’re in line with the front wheel.
The number that’s now visible on the gauge is your mountain bike’s head angle.

How To Adjust the Head Angle on a Mountain Bike

You may need to adjust your mountain bike’s head angle due to:

Changes in Terrain

You may need to change your bike’s head angle to fit your new terrain for a comfortable ride. In most cases, changes in terrain happen due to:

Relocation.
A change in the trails you frequently ride.
A change in the bike you’re using.
Upgrades to your bike.

These changes will affect your mountain biking experience, so you may need to adjust your bike’s head angle.

Rider Preference

Your riding style will also dictate the head angle of your mountain bike. If you’re a more aggressive rider, you’ll need a slacker head angle for stability when descending at high speeds. On the other hand, if you’re a less aggressive rider, you may want a steeper head angle for more comfort and control on your rides.

You can adjust your mountain bike’s head angle to fit your needs based on these preferences.

The following are some of the ways to adjust your mountain bike’s head angle:

Using a Bigger Front Wheel

A bigger front wheel than the rear wheel gives you a slacker head angle. Such a front wheel lengthens the distance from the head tube to the ground. The result will be a more stable bike when you are descending, giving you more control when riding at high speeds.

A bigger front wheel also raises your bike’s bottom bracket. This height gives you more clearance when riding over obstacles.

Consider using a 29-inch (73cm) front wheel and a 27.5-inch (69cm) rear wheel for an easier adjustment. Such an arrangement will give you a slacker head angle without significantly changing your bike.

The video below demonstrates how the front wheel affects your bike’s head angle:

Adjusting Fork Length

The fork’s length also dictates your mountain bike’s head angle. A longer fork will give you a slacker head angle, while a shorter one will provide you with a steeper head angle.

You can adjust your bike’s head angle without changing the length of the fork by:

Changing the Position of the Axle

If you have a quick-release axle, you can adjust its position to change the head angle of your mountain bike.

For a slacker head angle, move the axle forward. For a steeper head angle, move the axle backward.

This method is a simple way to adjust your mountain bike’s head angle without changing the length of the fork or the size of the front wheel.

Changing the Headset Spacers

If you have spacers on your mountain bike’s headset, you can remove them to adjust the head angle.

Removing spacers will make your mountain bike’s head angle steeper. On the other hand, adding spacers will make your mountain bike’s head angle slacker.

You can also change the height of your mountain bike’s stem to adjust the head angle. A higher stem will make your mountain bike’s head angle steeper. On the contrary, a lower stem will make your mountain bike’s head angle slacker.

Flipping the Chip

Some mountain bikes have a chip that you can flip to adjust the head angle. Flipping the chip will change the position of the linkages, which will, in turn, change the head angle.

Check your mountain bike’s manual to see if it has a chip you can flip to adjust the head angle.

Factors That Affect Head Angle in Mountain Bikes

Manufacturers design mountain bikes for different purposes, and as such, they have different head angles. The following are some of the factors that affect head angle in mountain bikes:

Intended Use

The intended use of a mountain bike will dictate its head angle. For example, downhill mountain bikes have a slacker head angle for stability when descending at high speeds.

On the other hand, cross-country mountain bikes have a steeper head angle for more comfort and control.

Suspension Design

The suspension design of a mountain bike will also affect its head angle. Mountain bikes can come with either:

A full suspension
Rear suspension.

Full-suspension mountain bikes have a slacker head angle than their hardtail counterparts. This slacker angle is because the front suspension absorbs some of the impacts, which would otherwise transfer to the head tube. Furthermore, this suspension raises the front wheel more.

As such, a slacker head angle is necessary to keep the front wheel in contact with the ground.

Frame Geometry

Frame geometry entails the length of the head, top, and seat tubes. These dimensions will dictate the head angle of a mountain bike.

A longer head tube results in a slacker head angle. On the contrary, a shorter head tube results in a steeper head angle.

Similarly, a longer top tube results in a slacker head angle, while a shorter top tube results in a steeper head angle.

The seat tube length also affects the head angle of a mountain bike. A longer seat tube results in a slacker head angle, while a shorter seat tube results in a steeper head angle.

In short, the longer the tubes, the slacker the head angle, while the shorter the tubes, the steeper the head angle.

Wheel Size

Mountain bike wheels vary from 26 to 32 inches (2.17 to 2.67 feet). Larger wheels have a longer axle-to-crown length. As such, they result in a slacker head angle.

On the other hand, smaller wheels have a shorter axle-to-crown length and, as such, result in a steeper head angle.

To sum it up, the larger the wheel, the slacker the head angle, while the smaller the wheel, the steeper the head angle.

Fork Length

Forks are essential in mountain bikes as they absorb impacts and smoothen the ride. They come in different lengths, affecting a mountain bike’s head angle.

It’s worth mentioning that 20 mm of fork length equals 1 degree. Therefore, increasing the length of your bike’s fork by 20 mm (0.7inch)slackens the head angle by 1°.

A longer fork results in a slacker head as it raises the front wheel. On the other hand, a shorter fork results in a steeper head angle as it lowers the front wheel.

As such, you should go for a longer fork if you want to slacken the head angle of your mountain bike. Otherwise, go for a shorter fork if you wish to steepen the head angle of your mountain bike.

What Is the Best Head Angle for a Mountain Bike?

Deciding on the best head angle for a mountain bike is a matter of personal preference. There is no overall best head angle for all mountain bikes.

The best head angle for you will depend on:

Your riding style: Mountain bikes with slacker head angles are more suited for aggressive riding styles, while mountain bikes with steeper head angles are best for casual riding.
The type of terrain: If you’ll be riding on technical and steep terrain, then a slacker head angle is ideal as it provides more stability. On the other hand, if you’re riding on flat and smooth terrain, a steeper head angle is perfect as it allows for more comfort.
Your height and weight: If you’re taller or heavier, a slacker head angle is ideal as it provides more stability. On the other hand, if you’re shorter or lighter, a steeper head angle is suitable as it’s easier to maneuver.

A good starting point would be a head angle between 67° and 69°. From there, you can adjust according to your preferences.

If you’re primarily riding on flat and smooth terrain, then you can increase the bike’s head angle. On the other hand, if you’re mainly riding on technical and steep terrain, then you can decrease the head angle.

Ultimately, it all comes down to personal preference. So, experiment with different head angles until you find one that you feel is comfortable.

Wrapping Up

A mountain bike’s head angle determines how stable you can ride on different terrains. While a slacker head angle is more stable, a steeper head angle is more maneuverable. Therefore, choosing a head angle based on your riding style, terrain type, height, and weight is crucial.

The good news is that you can adjust your bike’s head angle by using a bigger front tire, adjusting the length of the forks, and flipping the chip.

What Is the Head Angle on a Mountain Bike?