Understanding the parts of a bike is something that every cyclist will benefit from. Below you’ll find the most accurate and detailed parts of a bike diagram.
By learning each of your bike’s components and understanding basic bicycle anatomy, you’ll be back on two wheels faster if part of your bike breaks or requires maintenance.
Read this in-depth guide to bicycle anatomy, and you’ll develop a great level of understanding of what each bicycle component is and the function each part of your bike provides.
I’ll also direct you to some helpful maintenance information for parts of a bike that commonly cause issues.
Ready to become a bicycle component expert? Let’s go!
Bike Components Explained
Bike Frame Parts
Your bike top tube, also referred to as a cross-bar, connects the seat tube to the top of the head tube and runs parallel to the ground.
The length of your top tube dictates the position you’ll be riding in whilst cycling. A longer top tube provides a more aerodynamic and aggressive riding position, whilst a shorter top tube sacrifices aerodynamics for increased comfort.
The downtube is part of a bicycle frame that runs between and connects the bottom bracket to the head tube.
Down tubes often feature mounting points for water bottle cages and other accessories.
Additionally, the rear derailleur cables normally run along the underside of the down tube, whilst more modern bikes house these cables inside the down tube.
The seat tube runs up from the bottom bracket shell to the saddle, connecting the seat stays to the top tube, and the chainstays to the down tube.
A seatpost is inserted into the top of the seat tube, allowing you to sit down on your bike.
The angle of a seat tube greatly affects the overall geometry and riding position that different bikes provide.
A seat tube with a steep angle improves pedalling efficiency and aerodynamics, but reduces steering control and decreases stability.
A seat tube with a slack angle will provide a more stable and comfortable ride. But slack seat tube angles also reduce aerodynamics and make pedalling less efficient.
Seat stays are part of a bicycle frame that runs diagonally down from the top of the seat tube to the rear dropouts.
The seat stays run down either side of the rear wheel and are joined just above the wheel by a bridge or brace, increasing the frame’s rigidity.
Most of the time, this bridge provides mounting points for brake callipers, fenders or pannier racks. However, some seat stays provide their own brake mounting points, these are commonly found on bikes that use cantilever or V brakes.
Bicycle chain stays connect the rear dropouts to the bottom bracket shell and run on either side of the rear wheel, similarly to the seat stays.
Because the bicycle chain runs above the chainstays, many cyclists protect their chainstays with helicopter tape or a chainstay protector sleeve. These measures prevent dents and scratches on the chainstays when travelling on uneven terrain.
A bicycle head tube is the foremost part of a bike frame. The head tube houses the fork steerer tube and allows it to pivot freely on two internal sets of bearings (see headset below).
Rear brake cables tend to run along the underside of the top tube, whilst newer bikes house these cables inside the top tube.
The fork is the part of a bike that connects the front wheel to the frame. Two blades run from the bottom of the steerer tube, down either side of the wheel. These blades connect to the front wheel axle using their dropouts.
These two blades join together above the front wheel at the fork crown, which sits just below the steerer tube.
The steerer tube is part of the bike fork that runs through the head tube and attaches to the stem.
Both rigid and suspension forks are available:
|Rigid forks are commonly found on road bikes and provide increased speed on flat surfaces.|
|Suspension forks are typically used by mountain bikes and allow you to navigate harsh terrain whilst dampening and reducing the impact felt when tackling obstacles on the trail.|
Parts at the Front of a Bike
Most of the components towards the front of a bike play a part in the handling and control of a bicycle.
This area of the bike is comparable to a cockpit, with all of the navigation and speed control elements found here.
A bike headset is a rotatable bicycle component that sits on your fork’s steerer tube (above and below your head tube).
Bike headsets are made up of two cups. Each cup houses a set of bearings that allow your handlebars to turn smoothly.
A top cap is another key part of the headset, this is used to preload the headset before fixing the stem in place.
There are several different types of headsets available. Two of the most common are the Integrated System and threaded headsets.
A bicycle stem is one of the most important parts of a bike. A bike stem attaches the handlebars to the steerer tube of your front fork.
Because the stem is directly attached to the steerer tube, when the handlebars are turned, the front fork rotates with them, changing the direction of travel whilst cycling!
Some older stems are called quill stems which expands when tightened inside the fork steerer tube.
Most modern stems are front-loaded and have multiple screws so that you can remove your handlebars without having to remove the bar tape, brakes and gear shifters.
Headset caps (also called top caps and stem caps) are a bicycle component that’s used to preload (exerts pressure) the headset.
Bike top caps sit on the top of the fork steerer tube and are tightened (before tightening the stem) until there is no play or movement in the headset.
Once the stem cap is tightened correctly, the stem can be adjusted and tightened.
Handlebars are one of the most crucial parts of your bike’s anatomy. Bike handlebars are the bars that you hold onto whilst cycling and allow you to steer.
The handlebars of your bike are attached to the stem, which holds them in place. Some more modern bikes use fully integrated handlebars which combine the handlebars and stem into one single component.
Brake levers are found on the handlebars. A small cable known as a brake cable is attached to the inside of each lever.
When the brake lever is squeezed, the cable is pulled tight and causes the brake calliper to pinch the wheel rim or disc rotor, slowing the bike down or preventing it from moving.
Many modern bikes use STIs, which sounds questionable, but actually stands for Shimano Total Integration. STIs work just like normal brake levers but also have the ability to change gears compared to separate brake and gear mechanisms.
STIs are often referred to as shifters.
Grips & Bar Tape
When it comes to controlling your bike, the grips or bar tape you use is fairly important.
Road bikes and other road orientated bicycles tend to use bar tape.
Grips tend to be made from textured rubber, which allows you to keep hold of your handlebars without having to squeeze too tight. Grips also help to dampen vibrations, increasing your steering control.
Bar tape is much the same, it offers increased grip, cushioning and control of your handlebars.
You’ll probably want thicker, more cushioned grips or bar tape if you take long bike rides. These will keep your hands comfortable whilst cycling and make sure you maintain control of your bike.
Bar-end plugs or handlebar plugs are small plugs that slot into the end of your handlebars.
Plugs are installed to prevent injury in case of a fall or crash. Open-end handlebars are sharp and can easily puncture the skin.
Many cyclists have suffered fatal accidents where open-ended handlebars pierced through their abdomens, damaging vital organs.
Brakes are part of a bike that reduces the speed you’re travelling at by applying friction to your braking surface.
Nowadays, you only tend to find rim brakes and disc brakes. In the past, hub brakes were common on city and commuter bikes.
- Rim brakes come in three main types, calliper, cantilever and V brakes. These three rim brake types bring your bike to a halt by pinching the rim braking surface with a brake pad. Rim brakes are very popular and have been for a long time, but they aren’t as effective as disc brakes when riding at high speeds or in wet conditions.
- Disc brakes don’t use rims with braking surfaces. Instead, these modern brakes use callipers, which clamp down on disc brake rotors attached to the outside of your wheel. As explained above, disc brakes are more effective in wet conditions and are commonly utilised by mountain bikes.
Rim brakes and disc brakes are both engaged by squeezing a brake lever, whereas hub brakes are operated with your feet.
Cheaper bikes tend to use mechanical brakes, where a wire runs to the brake system and is pulled taught to engage the brake.
Hydraulic brakes are more expensive systems but provide increased braking control. Hydraulic brakes use a brake hose filled with fluid. When squeezing the brake lever, the liquid is put under pressure and causes the calliper to pinch down on the disc rotor.
Brake cables play a vital role in controlling your bike’s speed and play a key role in mechanical braking systems.
As you may already know, mechanical brake cables use an outer housing that protects the brake cable and allows it to move freely inside.
Brake cables are typically 1.5-1.6mm in diameter and come with different heads to suit various cycling disciplines.
Bike Wheel Parts
If you’ve ridden a bike before, then the chances are, you’ll know what a bike wheel is! But do you know each part of a bike wheel?
Bikes are normally sold with a stock wheelset (two wheels), but many cyclists choose to upgrade theirs as stock wheels tend to be low quality.
Several important parts make up a bike wheel. Below you’ll find information on all of the parts of a bicycle wheel.
Bicycle hubs are found at the centre of either wheel (front and back) and contain the bearings that allow your wheels to rotate freely.
Bike hubs are made up of five key parts:
|Hub Shell||The outer shell of the hub, often made from aluminium that houses the internal components and provides fixing points for spokes.|
|Axle||The axle of a bicycle hub runs through the centre of the hub and sits upon the internal bearings, which allow it to rotate. There are two main types of hub axles, quick release axles and through axles. Axles also attach your wheel to the dropouts of your bike.|
|Ball Bearings||The ball bearings of a bike hub sit inside the hub shell cup and allow the wheel to rotate smoothly. If your wheel isn’t rotating properly, then a likely cause of this is that your ball bearings are worn out.|
|Cones||Cones are found on adjustable hubs and work alongside lock nuts. Cones play a part in tightening or loosening the hub’s bearings. If your cone is too loose, the hub may have play in it, and if the cone is fitted too tightly, the wheel will not spin freely.|
|Lock Nut||Lock nuts are used to lock the hub’s cones in place after adjusting them to the correct level. Once the lock nut is tightened, it will hold the cone in place. However, be careful not to overtighten the lock nut as you may end up tightening your cone!|
Bicycle rims come in many shapes and sizes and nowadays tend to be made from aluminium. Spoke nipples are threaded through the rim, and screw onto the spokes, holding the wheel together.
Tires are attached to the rim. Clincher tires attach to clincher rims which house an inner tube. Tubular tires attach to tubular rims and encapsulate the inner tube.
Wider, thicker rims tend to be stronger, whilst thin, lightweight rims provide increased aerodynamics and speed.
Before the invention of disc brakes, most bike rims had a flat braking surface that the brake pads squeeze to lower riding speed.
Bikes that use disc brakes do not require a braking surface and instead use disc rotors that serve the same purpose.
Spokes are the rods that connect the rim of a bicycle wheel to the hub. Spokes bear the weight of the rider and bike, so they must be installed and tensioned properly.
Overtightening, bicycle spokes can damage the rim, hubs and spoke nipples of your wheel. Poorly tensioned spokes can also cause the wheel to be misshapen (often egg-shaped).
Adjusting the spokes of a wheel to roughly the same tension will provide a strong, reliable wheel. To find the ideal spoke tension for your wheel, check the recommended tension with your rim manufacturer.
Spoke nipples pass through the wheel rim and are tightened onto the end of the spoke. As the spoke nipple is tightened, the tension of the spoke increases, increasing the tension on the hub.
Since spokes and spoke nipples need to have the same thread, spokes are normally supplied with matching threaded nipples.
Bike tires are the part of a bike wheel that makes contact with the ground whilst the wheels roll. Different types of bikes use different tires.
Mountain bikes use wide, heavily treaded tires that provide vibration dampening and increased traction.
Road bikes use thinner tires that have minimal tread, providing decreased rolling resistance.
There are three main types of bike tires, clincher, tubular and tubeless.
|Clincher Tires||The vast majority of bicycles use clincher tires, which work in conjunction with and are attached to clincher rims by their two inner metal beads. An inner tube sits inside a clincher tire which is inflated before riding.|
|Tubular Tires||Tubular tires are commonly only used by road bikes and are designed for racing. Because tubular tires are glued to the rims, they aren’t limited by the rim's sidewalls. This means tubular tires provide better shock absorption than clincher tires of the same size.|
|Tubeless Tires||Tubeless tires are a fairly new concept. Tubeless tires can be fitted to most clincher wheels but may require a special rim strip to keep the tire airtight. As you probably figured, tubeless tires don’t use an inner tube and are filled with sealant to encourage an airtight seal with the rim.|
Valves on a bike wheel are the air inlets that allow you to inflate your tires. Historically, there were many different valve types, but Schrader and Presta valves are the two main options nowadays.
Schrader valves are the same valves you find on car tires and motorcycles. To inflate a Schrader tire, the spring-loaded pin in the centre of the valve must be depressed. Once this pin is pushed down, the valve is open, and the tire can be inflated.
Presta valves are mainly used by road bikes. Presta valves are thinner than Schrader valves and seal tightly on air pressure alone. This means they don’t need to use a complex valve, reducing their overall weight.
Bicycle Drivetrain Parts Explained
Crankset / Chainset
A bike’s crankset, also called a chainset, comprises three integral parts of a bike’s drivetrain.
Cranks arms, chainrings and a bottom bracket make up the crankset. The crankset is the part of a bicycle that transfers the rotation of your legs, to your rear wheel through the chain.
Single, double and triple are the three formats that cranksets come in; these formats relate to the number of chainrings the crankset employs.
Pedals are attached to the crank arms, which allows the rider to turn the chainset.
A bottom bracket is a bicycle component that sits inside the bottom bracket shell at the bottom of your bike frame and connects either side of the crankset using its spindle.
The bottom bracket contains ball bearings that allow the central spindle and cranks to rotate freely whilst pedalling.
Cheap bottom brackets will provide around 8000km (5000 miles) of cycling. Of course, this figure will change depending on riding conditions and how often you carry out bike maintenance.
Bike pedals are the part of a bike that connects the rider to the drivetrain.
Put simply, bike pedals act as a platform for you to stand on and push whilst cycling to provide power to your back wheel.
Bike pedals come in many different types. Platform pedals are the most common type of bike pedal and are suited for recreational and non-competitive cycling.
For competitive and more intense cycling, cyclists often opt for clipless pedals. Clipless pedals require special shoes that connect directly to the pedals and increase pedalling efficiency by up to 10%.
The front derailleur is a key part of bicycle anatomy. When tackling a big hill or hitting flat roads, the front derailleur is the part of your bike that allows you to shift up and down on your chainrings, reducing or increasing the difficulty of pedalling.
Front derailleurs are only found on bicycles with more than one chainring. Bicycles with a 1x drivetrain setup use a single chainring and therefore do not need a front derailleur.
Front derailleurs are attached to your bike’s frame with a bracket or clamp and are operated using your gear shifters.
A chain is the component of a bike that transfers the rotation of the crankset (from pedalling) to the rear wheel of your bike.
A bicycle chain sits on the chainrings and the cassette of the rear wheel. When pedalling, the chain moves in motion with both of these components rotating the back wheel.
Normally you can expect a standard bicycle chain to last 3,200-4000km (2,000-2,500 miles) before needing to be replaced. However, bicycle chains need to be regularly cleaned and lubricated to maintain reliability and efficiency.
When changing gear, the bicycle chain is shifted on the chainrings and cassette by the derailleurs.
A rear derailleur is the bicycle component that transfers the chain between the sprockets of the cassette on the rear wheel.
When shifting to the smaller sprockets on a cassette, the bicycle chain has more slack. Subsequently, the rear derailleur plays another role in maintaining chain tension when shifting through your rear cogs.
The rear derailleur on a bicycle contains two similar jockey wheels, but either jockey wheel plays a different role.
The upper jockey wheel, commonly called the “guide pulley”, is in charge of shifting gears and guides the chain across the sprockets on the cassette.
The lower jockey wheel or tension pulley controls and maintains chain tension when shifting gears.
Cassette / Cogset
A cassette is an essential component of the bicycle drivetrain and is made up of a group of sprockets (cogs) located on the freehub of the rear wheel.
Modern bicycle cassettes normally use between 8 to 11 sprockets, whilst other cassettes are available with 5 to 13 sprockets.
Bike Seat Parts
Saddle / Bike Seat
A bicycle saddle also called a bike seat, is one of the key components of your bike. As a point of contact, you sit on your saddle whilst riding. Saddles come in many shapes and sizes.
Some saddles are wider, with increased padding for extra comfort, while others focus on speed, minimizing padding and width to keep weight to a minimum and avoiding thigh chafing.
Saddle rails are the two parallel rails that run along the underside of your bike seat. These rails are connected to the top of the seatpost and can be made from a wide range of materials.
On the saddle rails, you’ll find fore and aft measurements. These are used to determine correct saddle positioning.
Seat posts, seat pillars, seat pins, saddle posts, and saddle pillars are different names for the post that extends from the bike seat tube and attaches to the underside of the saddle.
Seatposts are adjustable in height, allowing cyclists to optimise their bike’s geometry to their desired riding position.
When adjusting a seatpost, it’s important to pay attention to minimum insertion markings on the seat post tube. Seat posts that are over-extended can easily damage a bicycle.
Seat Post Clamp
Seat post clamp can be found at the top of the bicycle seat tube. These clamps are a metal band or collar that tightens the top of the seat tube, holding the seat post in place.
Whilst most seat post clamps use a band or collar mechanism, others may use a single bolt to tighten the seat post.
Summary - Parts of a Bike Diagram
If you’ve read through this guide you should now understand a little more about the components of a bicycle and the role that each part plays.
If you missed it, at the top of this page you’ll find a bike parts diagram which is labelled and colour coded to help you learn.
If you think I’ve missed something out, leave me a comment below and I’ll get back to you.
If you ever find yourself worrying about the security of your bike, you’ll want to increase its security. Have a read of my guide on the best cheap bike locks for some great recommendations.
As always lock it or lose it.
Ciao for now!