Welcome to our comprehensive guide on the essential parts of a mountain bike. Whether you’re an avid rider or just starting out, understanding the components of your bike is crucial.
Mountain bikes are an intricate blend of simplicity and complexity, and we’re here to break it down for you.
1. Frame
The frame is what every part of the bike is fixed to and functions like the bike’s skeleton. Its purpose is to be light and strong while also having enough flex to handle the vibrations without cracking. Most modern mountain biking frames are made of aluminum alloy or carbon fiber, but you can also find more niche frames like steel or titanium.
The frame typically consists of two sections or triangles. The parts that make up the front triangle of the bike are called tubes. While the parts that make up the rear triangle are the stays.
In the front triangle you have your top tube, head tube, down tube, and seat tube. In the rear triangle you have the seat stays and the chain stays.
Full suspension bikes will be a little more complicated and include linkage where the rear shock attaches to the frame. We’ll talk more about that with the rear shock.
2. Seat Post
The seat post is used to attach the saddle to the bike. The seat post is inserted into the seat tube and held in place with a clamp. You can adjust your saddle height by loosening the clamp and sliding the seat post up or down to reach the desired height.
There are two main types of seat posts: Standard seat posts and Dropper seat posts.
A standard seat post is basically a metal or carbon pipe with the saddle attachments at one end. This is what every bike used to have and you still find them on less expensive bikes and on some high end racing bikes looking to save weight.
A dropper seat post uses hydraulics to enable you to adjust your seat height without stopping and getting off your bike. They’ve changed the way mountain bikers ride and are a great addition to any set up.
3. Seat/Saddle
The Saddle or bike seat is the part of the bike you sit on while pedaling. They are designed to be ergonomic and you can get different sizes based on your own anatomy. Most mountain bike seats do not have a lot of padding, so it can take some getting used to at first.
4. Stem + Headset
The stem and the Headset are how the handlebars attach to the front of the bike. The headset isn’t clearly pictured on our diagram above, because it sits inside the head tube of the bike and around the steerer tube (the steerer tube is part of the fork which we’ll discuss in section 12). The headset is made up of bearings and rings that make it so that the steerer tube can rotate.
The stem is essentially one piece that clamps vertically to the steerer tube and horizontally to the handlebars. They come in a variety of lengths and angles depending on the rider and the type of riding they do.
5. Grip
The grips go on both ends of the handlebars. When choosing grips you want to make sure that they are comfortable, but also help you maintain control of your bike. They are usually rubber or foam and vary in levels of cushion and grippiness.
Some grips have small clamps on them that you can tighten down to prevent the grips from moving while you are grabbing them. This can be an important feature to help you keep control of your bike, but it also makes the grips easier to remove later.
6. Handlebars
Mountain bike handlebars are like the cockpit of the bike. This is where everything you need to control your bike is attached. Modern mountain bike handlebars are made of either aluminum or carbon fiber and tend to be much wider than older bikes.
The handlebars come in a variety of widths based on the size of the rider and riding style. You can also find handlebars where the grips sit higher than the center of the bars. This is called rise and can be advantageous when riding downhills.
Attached to the handlebars you’ll find your grips, shifters, brake levers, and dropper post levers.
7. Shifter
Shifters are how the rider controls the shifting of the bike’s gears.Your shifters are typically attached to the bike right next to your grips and within easy reach of your hands when riding the bike. Some bikes will have both a front and rear shifter, but most modern mountain bikes only have one that goes to the rear.
They’ll have two switches on them that will either shift the bike up or down in gears. The shifter will normally have a cable that goes from the shifter through the down tube of the bike to the derailleurs. Some high end bikes have cableless shifting.
8. Brake Levers
The brake levers are also clamped to the handlebars and the levers typically fit just below the shifter. The brake levers are meant to be squeezed towards the grips in order to stop the bike. Ideally brakes should be set up so that you can pull the brakes with just one finger, though this is hard with older and less expensive brakes.
The brake levers consist of two main parts: the actual lever you pull and then the hydraulic reservoir the levers are attached to. On hydraulic brakes the reservoir contains mineral oil that connects to the brake calipers via a brake hose.
9. Brake Caliper
The brake caliper is what squeezes the brake rotor stopping the bike. The caliper will be attached to the frame of the bike and will have two brake pads on either side of the rotor. When the rider squeezes the lever the pressure increases in the brake hose which causes two pistons to push the brake pads together stopping the rotor from turning.
Most modern brake calipers work hydraulically, but some brake systems still use a cable similar to your shifting.
10. Brake Rotor
The brake rotor is a metal disk that is directly attached to the wheel. When the brake caliper stops the rotor from turning it also stops the wheel from turning at the same time. These come in different sizes which can affect how easy it is to stop the bike.
11. Hubs
The hubs are the center of the wheel and are actually one of the more complex components of the bike. They come in a lot of different variations and sizes, but at their core they serve 3 main purposes:
- They are the center of the wheel and are essential for holding it together with the spokes.
- Attach the wheels to the bike.
- Attach the Cassette to the Wheel. (Rear Hub Only)
- Attach the Brake Rotors to the Wheel.
12. Fork
The fork of the mountain bike holds the front wheel and enables the bike to turn smoothly. In modern mountain bikes, almost all forks are suspension forks, providing enhanced cushioning and stability while riding.
Suspension forks are designed to absorb impacts and vibrations encountered on rough terrain. They consist of a system of springs, dampers, and telescopic tubes that allow the fork to compress and rebound, providing a smoother ride and better control over obstacles.
The top of the fork is the steerer tube which is inserted through the bottom of the head tube and attached to the handlebars on the other end of the head tube. Most steerer tubes are tapered for increased strength.
13. Wheel
The wheel is the combination of the hubs, the spokes, and the wheel rims. The wheels are attached to the bike with a thru axle or a quick release axle.
Mountain bikes have come in several sizes over the years, but most modern mountain bikes are either 27.5 inches or 29 inches depending on the size and style of the bike.
Mountain bike wheels can be made of either alloy and carbon.
14. Tire/Tyre
Tires (or Tyre’s in the UK) are the rubber part that goes around the wheel. Like a car tire they come in different widths and tread patterns for different kinds of riding. Most mountain bike tires are between 2” wide and 2.8” wide.
Mountain bike wheels and tires can either be set up to be used with tubes or without tubes. When a tubeless set up is used the tire will be seeded in the wheel and sealant will be used to help the bike stay inflated.
15. Pedal
Bike pedals are threaded onto the cranks. There are two main types of mountain bike pedals: Flats and Clipless pedals. Flat pedals are usually made of plastic or metal. Most flat pedals have studs on the surface to help grip the shoes.
Clipless pedals have clips that can attach to cleats on cycling shoes. These are especially used for cross country mountain biking where riders are trying to achieve maximum efficiency.
16. Chainrings and Crank
A mountain bike has two sets of gears. The gears on the rear wheel are called the cassette and the gears attached to the pedals are called the chain rings. The chain rings are attached to the pedal cranks and as you turn the cranks with your feet you turn the chain on the chain rings.
Most modern mountain bikes have only one chainring but some bikes have 2 or 3 chainrings. Some bike component manufacturers have also started producing oval chain rings to make pedal strokes more efficient.
17. Rear Shock
Full suspension bikes have a rear shock on them. Mountain Bike rear shocks are typically made with either air or metal coils.
There are a few different designs of full suspension bikes, but in all of them the rear shock connects the front triangle to the rear triangle via linkage and pivots.
18. Front Derailleur
The front derailleur has become increasingly uncommon in modern mountain bikes with most bikes opting for simpler one chainring setups. You’ll still find them on some bikes though. The front derailleur is connected to one of the shifters by a cable.
The front derailleur is responsible for guiding the chain between the different chainrings (usually two or three of them) and keeping the chain in the right spot while riding.
19. Chain
The chain is one of the most familiar bike components to most people. The chain is a series of interlocking links and one master link. The master link is one link that can be easily opened with special pliers. This is good for maintenance. You can also use a master link to fix a broken chain in a pinch.
The chain is the central part of the drivetrain which includes the chain, cassette, chainrings, cranks, derailleurs, and shifters.
20. Rear Derailleur
The Rear Derailleur is one of the most dynamic components on the bicycle. The rear derailleur is used to gear up or down the rear cassette. It is highly adjustable to help you tune your bike to shift smoothly.
The derailleurs can be made with plastic and metal parts. You can also now get cableless derailleurs.
21. Cassette
The bike’s cassette is the gears for the back tire. Most bikes now have anywhere from 9 to 12 gears. The cassettes will also tell you how many teeth the smallest and the largest gears have. The cassette is attached to the back wheel and can only be removed with specific tools.
Some cassettes like the Sram Eagle cassettes are one solid piece, while other cassettes may be made up of a stack of separate gears.
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