Parts of A Bike Diagram | The Bicycle Anatomy Guide for All

Almost everyone is familiar with a bicycle and how to ride one, but not a lot of people know what the anatomy of a bike is and all of the little components that go into making such a timeless vehicle.

This guide will provide lots of important information about bicycles, giving beginners and amateurs some knowledge that may help them fix their very own bicycle one day.

As well as this, you simply may find bicycle anatomies interesting, and if that’s the case then this is a perfect place for you too! Each section of the bicycle anatomy will be broken down into parts to make it easier to follow.

These sections will consist of the frame, seat, wheels, and front and back of the bike. 

We will also be discussing the technical jargon that is commonly used when talking about bicycles so that you don’t get lost along the way!

That’s not all, because we will also be covering the common issues you may experience with your bike and how to repair them, making this an ultimate bike guide for everyone. 


The frame is what brings the whole bike together and tend to be stiff, light, and strong with the most common style of frame called a ‘diamond frame’ which has six tubes to create two triangles known as the main triangle and rear triangle that attach to one another via the seat tube. 

Frame Materials

Bicycle frames are traditionally made from steel or aluminum alloy with high-end bikes being made of titanium or carbon fiber. 

Carbon Fiber

If you are after a bike that is lightweight, then you would probably get one that has a carbon fiber frame as it has a low density whilst being able to absorb the vibrations from the road which gives you more control as you ride.

Carbon fiber is also a relatively easy material to work with as it can be formed into many different shapes, but this high-quality material also means a high price tag and if you are not particularly interested in bicycles then it may not be for you. 


Aluminum bicycle frames are very popular because they are strong, light, and affordable. Aluminum is not as good as carbon fiber for absorbing road vibrations, but they still offer good stiffness that makes them easy to handle when riding. If smooth, comfortable rides are important to you then you should maybe look elsewhere. 


Steel bike frames are somewhat a thing of the past but are still being used today for those who like their design to be custom made for them, and steel is strong, durable, and is easier to repair which is very cost-efficient in the long term.

However, the reason why it is not as popular as other materials today is that it is heavy and has a high initial cost. 


Titanium is more resistant to corrosion than steel frames and provides the same amount of comfort as carbon fiber frames. Titanium bicycle frames have a lot of benefits, but it is hard to get your hands on as it’s quite rare because an awful lot of work goes into manufacturing them. 

Top Tube

A top tube is also known as a crossbar and is the part of the fame that you have to swing your leg over to get onto the bike, particularly if it is a bike with a tup tube that runs parallel to the ground. However, you also get frames that have a top tube that is more sloped or no top tube at all to make it easier to get on and off. 

Head Tube

The short tube at front of the bike that connects the handlebars and the wheel fork together is called the head tube or steering head. The headset is contained in this tube and is used to turn the handlebars. It also tends to bear the bike’s logo which is known as the ‘head badge’.

Down Tube

The down tube is the long, thick part of the frame that stretches from the head tube to the pedals. This bar is made strong and thick so that it can put up with the amount of force experienced during riding. 

Seat Tube

The seat tube is the bar that runs from underneath the saddle to the pedals. This is where the seat post is inserted, and the height of the seat can be adjusted by how far down the seat post sits inside the seat tube. 

Seat Stays

The seat stays are two long, thin tubes that stretch from the saddle to the wheel hub at the rear. These seat stays end at what is known as a ‘rear drop out’ which are connected to the axle of the rear wheel. 

Chain Stays

There are another two thin tubes that run from both sides of the pedals to both sides of the rear wheel. They get their name from the fact that they run parallel along the ground beside the bicycle chain. 


The seat of the bicycle is a very important part of what makes a bike ride enjoyable. Seat saddles can come in different shapes and sizes and they are easy to take on and off.

Generally, women will find wider saddles more comfortable, and men would prefer a narrower one. 

Finding the right saddle for you also depends on the type of cycling you like to do, for instance, do you use your bike for commuting or for tearing along dirt trails?

If you only really use your bike for commuting, then you will not need to worry too much about the saddle as you will not be on it for too long and likely won’t be cycling over bumpy terrain.

Therefore, if you like to cycle for sport then it is much more important to have a seat that is comfortable.

An effective way to find a saddle that is comfortable for you is by measuring your sit bones which is the lower part of your pelvis that you can feel make contact with the seat as you sit down.

Once you have measured the distance between your sit bones you can use this measurement to find a seat that matches this width. 

Now that you have found the perfect seat, you must have it at the right height, if you do not have it at the right height then your pedal strokes will be less efficient, and you may feel your back start to ache from sitting in an unnatural position. 

You will know when your seat is at the right height if the heel of your foot grazes the bottom of the pedal when you are in the 6’oclock position.

If you notice pain in your knee when you are cycling, it is an indicator that you need to slightly raise your seat. The backs of your knees will also tell you when you need to lower your seat by becoming painful as you ride.

A common mistake that people make is thinking that their feet should be flat on the ground as they sit on the saddle, however, this is a sign that your seat is far too low as you should only be able to touch the ground with your tiptoes. 

As well as changing the height of the saddle, you can also change the angle but this tends to be done only by athletes or very experienced cyclists.

Otherwise, it is advised to have your seat horizontal because if it is too far back or too far forward then you can experience back, neck, and arm problems.

Once you have found the right position, and you do not experience any pain when riding, then you have the freedom to make very slight adjustments to the angle of the seat for extra comfort.  


This saddle is the part of the bike that you sit on as you ride, and as explained earlier can come in various different shapes and sizes as well as material so that everyone can find the right saddle for them.

There are saddle rails underneath that connect the saddle to the seat post with the saddle clamp. 

Seat Post

The seat post goes inside of the seat tube and is kept in place with a clamp which is also used to adjust the height of the seat. 


Obviously, there is no bike without wheels. However, over the many years that bicycles have been around, wheels have become much more specialized in what their purpose is.

Today there are different types of bicycle wheels such as road wheels, mountain bike wheels (MTB), and hybrid wheels. 


The hub is made of three parts called the bearings, hub shell, and axle. The bearings are between the axle and the hub shell so that the hub shell can spin around the axle.

The hub shell is what the spokes are attached to and the hub sits in the middle of the wheel and attached to the front and back is an axle that attaches the wheel to the bike and provides the axis of rotation. 


Rims are usually made from aluminum alloy and is the circle of metal that forms the circumference of the wheel. Brake pads are used to grip tightly onto the smooth surface of the rim.

The most common rim size for a bicycle is from 26-inches to 29-inches, with kids’ bikes having rims that are smaller than 24-inches. 


The spokes are what connect the rim and the hub together, they are designed to apply equal tension in every direction. Spokes play a big part in making a wheel strong, and stable, and able to carry heavy weights without bending at all.

The number of spokes that a wheel has differs between the front and rear wheel, with the rear wheel having slightly more so that it can withstand more force.

However, the more spokes a wheel has, the heavier it becomes and the material that they are made from alters how aerodynamic and strong they are. They are usually made from steel wire but can come in different shapes and diameters. 


The tire fits over the top of an inner tube that is filled with air to provide suspension and is mounted onto the rim. They are made from rubber impregnated cloth and have an outer layer that is made from a thicker rubber for the tread.

Depending on the type of wheel, their tread will vary with road bikes having less tread and mountain bikes having much more. 


The nipples are the small nuts that are on the inside of tires that attach spokes to the wheel, they are also used to adjust the tension of the spokes so that it is not wobbly when spun. 


The valve used on a bicycle is known as a presta valve, but you may also see schrader valves. The valve is what allows you to add air to your tire and it sticks out through a hole in the wheel rim. 

Front of the Bike

These are all of the components that you can find at the front of the bike. 


The fork gets its name from the fact that it has ‘fork blades’ that stretch down from the head tube to each side of the front wheel. At the top of the fork, the steerer tube sits inside which is connected to the headset.


The headset is what sits inside of the head tube and connects the frame to the wheel fork. When you turn the handlebars, the bearings in the headset makes the front wheel turn. 


The fork’s ‘steerer tube’ is connected to the handlebars via the stem and can be seen sticking out from the top of the head tube with the handlebars running through the end of it.  


The handlebars are another part of the bike that everyone should be familiar with as it is the part that you hold onto to steer the bike.

Handlebars are connected to the bike frame through the stem and they can come in different styles depending on the type of bike.

Mountain, urban, and hybrid bikes have flat handlebars and road bikes have drop handlebars, but they can come in other designs too such as bullhorns and pursuit bars. 

Brake Levers

Some bikes do not have brakes, but most do, with one controlling the front brake and one controlling the rear brake. They are placed on the handlebars, and you squeeze them to slow down or completely stop.

There are visible brake cables that lead from the brake levers to the brakes. Hydraulic fluid is passed down through these cables and when the brake lever is pressed, pressure is applied to the fluid in the cable and makes the piston at the wheel squeeze. 


There are two types of brakes that are used on bicycles, disk brakes, and rim brakes. 

Disk brakes use a metal disc that is attached to the wheel hub and work particularly well in wet conditions and are most commonly used on mountain bikes but are getting more popular with other types of bicycles in recent years. 

Rim brakes apply pressure to the rim of the wheel (hence the name) and they are popular due to them being cheap, light, powerful, and easy to maintain. Despite this, they are not as effective as disk brakes in wet conditions which can make them quite dangerous if you’re not careful. 

Back of the Bike  


This is the mechanism that powers the bicycle and consists of the part where the chain goes round called the chainrings and the crank arms which is where the pedals are attached.

The chainrings are the gears at the front of the bicycle and there are up to three of them on a geared bicycle and only one on a single-speed bicycle. The bottom bracket attaches the crankset to the frame, the chain attaches it to the rear wheel and the pedals to you. 


The pedals are what you apply pressure to with your feet to make the bike move. There are two types of pedals including the platform pedal and clip-in pedal.

The pedals that you have likely used before are the platform ones and you simply rest your foot on top of it. The clip-in pedal requires you to use specific shoes that have cleats on the soles so that you can securely attach your feet to the pedals, they are mostly used for competitive sports. 

Bottom Bracket

The crank arms rotate around the bottom bracket which is the part of the bicycle that consists of bearings that allow for smooth rotation of the spindle which is attached to the crankset. The bottom bracket has a shell that it slots into at the frame base. 


The chain is what connects everything together so that when you push the pedals the rear wheel moves. The chain goes around the crankset’s chainrings and along the chain stay before going around the sprockets of the rear wheel’s cassette. 


The cassette consists of different-sized sprockets that are attached to the rear wheel’s hub. These cassette cogs are the gears for the rear wheel and will only be there if your bicycle has multiple gears. 

Front Derailleur

As you shift gears, the front derailleur moves the chain between chainrings. This means that single-speed bicycles do not have derailleurs. 

Rear Derailleur

The rear derailleur moves the chain between cassette cogs on the rear wheel when you change gears and works together with the jockey wheel. 

Jockey Wheel

The jockey wheel is what keeps the chain running smoothly by maintaining tension as you change gear. Even bicycles with one gear can have a jockey wheel as a chain tensioner. 

Technical Bicycle Jargon 

This is a list of other bicycle jargon that has not been covered earlier but is still good to know about.

  • Bar ends – angled extensions of some flat or riser handlebars that allow you to place your hand in a different position.
  • Braze-ons – sockets that are attached to the frame of the bicycle that you can use to put accessories in such as a water bottle or fender. A cage is another word for a braze-on on a bike to store a water bottle.
  • Cog – the name given to one gear on the freewheel cluster or cassette, as well as the single gear on single-speed bicycles.
  • Cyclocomputer – a technical term for a speedometer or odometer.
  • Derailleur hanger – the part of the frame where the derailleur is attached. It is a replaceable component on carbon fiber and aluminum bicycles rather than integrated on titanium and steel bicycles.
  • Droupouts – notches on the rear of the frame and the bottom of the front fork legs that uses a U-shape design to hold the wheels in place. It gets the name from the fact that if you loosen these notches, the wheel will drop out. 
  • Fixed gear – refers to a bicycle that only has one gear and does not have a cassette making you unable to coast and you must pedal if the wheels are moving. 
  • Freehub body – section of the hub on the majority of rear wheels and provides the mechanism that allows you to coast.
  • Freewheel – the gears on the rear wheel that are more common on older bicycles or ones that are lower-end. The freewheel consists of both the gears and the coasting mechanism, unlike the cassette gears where the gears are a solid component. 
  • Rim strip – a piece of material such as plastic, cloth, or rubber that is put around the outside of the rim to stop the spokes from puncturing the inner tube.

Common Bicycle Breakdowns

The harsh reality of life is that bicycles break down sometimes, but like any vehicle, the more care you take with them the fewer problems they will give you.

Here are some of the most common issues your bicycle might experience throughout its lifetime and how you can repair them.

Now that you know the bicycle anatomy, this section will be a lot easier to understand and it won’t be as overwhelming when something goes wrong. 


This can happen to pretty much any vehicle that has tires but is extra troublesome when it happens on a bicycle because you can’t just get a spare one from out of the trunk.

A blowout happens when the tire gets damaged and all of the air is lost at once, creating a tiny explosion of air that is sometimes powerful enough for the wheel rim to blow off. 

Carrying some extra tubes and a portable tire pump with you on your rides can be a lifesaver, and in this instance, you will be very thankful you brought them. As well as a new tube, you will also need some thin paper or dollar bills ready for this trick.

First, remove the wheel from the bike and fold the paper into thirds before tucking it between the new tube and the damaged hole in the tire. Then, pump up the tire until it reaches 20 to 30 lbs, and you’re ready to cycle home where you can get access to a more permanent repair. 

Broken Chain 

As chains are so delicate, they don’t break as much as you may think they do but they are still known to have some issues every now and then. The way you can usually tell when a chain breaks is when you hear a big clunk noise and your pedals have no more resistance as you push, leaving you stranded.

This is why it’s really important that you bring tools such as a chain breaker and a master link whenever you go for a bike ride. 

A chain breaker works by replacing the sections of links in the chain that has broken. It may seem a bit fiddly at first, but with a bit of practice on a spare chain, you will get the hang of it in no time. 

A master link is the other tool that will be a great help if your chain breaks. You can get one from any bike shop and make sure that it is the same size as your chain. To use a master link is a bit more complicated than a chain breaker but is still very doable for any bicycle amateur.

Begin by putting the bike in the lowest gear and feeding the broken chain through the derailleur, then use the chain breaker to remove and of the broken chain links, this will create two holes on both sides of the chain.

These holes are where you will insert the missing link through and click it together, give the pedals a bit of a push, and if your bicycle begins to move then you’ve done it right. 

Broken Derailleur 

Derailleurs are usually pretty durable and if you happen to bend one, it can be bent back with your hands. However, the axle of the jockey wheel can cause some problems with gears becoming loose.

To fix this, you will need to have a hex wrench on you to insert through the center to act as the axle but I you don’t have one you can use a stiff bit of wire instead. 

Broken Cables

If you break a cable on your bicycle, they are much harder to fix and are best taken into a shop for a professional to take care of. Fortunately, you won’t be stranded in the middle of nowhere like a blowout or a broken chain would.

If you break the front derailleur cable, your bicycle will react by ‘cross-chaining’ which is a term used for the bicycle shifting to the small ring on the front but will still give you access to the back gears. It’s a bit of a noisy problem but you are still able to ride home or to a bike shop without causing any permanent damage. 

The rear derailleur cable behaves differently to the front one, so if this cable breaks the bicycle will shift straight to the highest gear and cannot be shifted to a lower one unless you do some fiddling about with the cables and the shifter.

To do this, you take the broken cable out of the shifter and pull the cable tight as you shift gears. Once you have selected a lower gear, you must tie a knot in the cable and secure it with zip-ties to keep it secure on the frame. It sounds like a bit of a job but it might beat having to cycle home on a high gear and having jelly legs the next day. 

Loose Handlebar and Stem

This is another common inconvenience that cyclists experience now and then and is usually down to a bolt loosening or falling out. This is when you reach for the spare 4 or 5mm bolts that you have packed with you prior to leaving the house so that you can quickly pop them in and set off again.

However, if you didn’t bring any extra bolts you can take one from the bottle cage or from somewhere else that isn’t essential to the bike’s performance. 

Broken Seatpost

A broken seatpost can be very uncomfortable when it happens but there is an easy temporary fix that will get you home in one piece.

All you have to do is take off the broken piece of frame and put the shortened seatpost and seat back into the frame. You will be low down and probably have an achy back when you get home but it could be worse. 

Another issue you may have with a seatpost is when the seatpost clam breaks and you have to replace the whole clamp when this happens. As a temporary fix, you can use zip ties to keep the clamp and seat together for the ride home.

Andrew Daniels