Cycling - Knowledge

Bike Anatomy: Do You Know Your Bicycle?

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You might have been biking for some time now but, are you aware of all the components of a bike? Of course, you might know what handlebars, pedals, seat, spokes, chain etc but have you ever heard of cranks, Derailleurs or rear sprockets? Most probably not. These aren’t the terms that most people know. But, if you are a passionate biker and wish to expand your knowledge, learning about bike anatomy would open up a whole new world to you.

road bike anatomy
A Detailed Anatomy of Road Bike

Even if you wish to learn about the basic bike maintenance, you would need to about each and every part of a bike in detail along with their functions. Follow this guide to learn about the concept of bike anatomy to understand your bike better.

Frame: Most Important Component in Bike Anatomy

bike anatomy frame
The Body of a Bike (Source)

In bike anatomy, the frame is the most important component as it is basically what forms the bicycle. It might be made of steel, aluminium, carbon-fibre or titanium. It is the main component onto which the wheels and several other components are fitted. The modern frame design of a bicycle consists of two triangles: one main triangle and a paired rear triangle. This is referred to as the diamond frame. Frames generally have to be stiff, strong and light. This is achieved by combining several different materials as well as shapes.

The frame can be split into different areas. As can be seen in the diagram above, there’s a head tube that is a vertical section through which the fork is fitted. Then there’s this tube that runs diagonally from the top to the pedal are and is referred to as down tube. The top tube runs from the head tube and towards the saddle. All these together form the main triangle.

Now, in the anatomy of a bicycle, if you look, you would notice that there’s another triangle referred to as paired rear triangle or the smaller rear triangle. There is one tube that runs from just below the saddle on either side of the rear wheel and is referred to as seat stays. The other two tubes that run on either side of the rear wheels exactly from behind the pedals are known as chainstays.

Fork: What Gives Your Bike Direction

bike anatomy fork
A Fork in the Road (Bike) (Source)

The fork is the front part of the bicycle that is responsible for holding the front wheel. The fork typically has three parts: the crown, the steerer tube and the arms. Now the fork has two blades that are joined together by the top of the fork crown. Exactly above this crown is a steerer tube which sticks out from the crown and attaches the fork to the handlebars and this is what allows the user to steer their bicycle.

These steerers can be either threaded or threadless. The steerer tube merges with the frame with the help of the bearings that is known as a headset and is mounted on the head tube. The dropouts hold the wheel together at the fork’s bottom. the axle is either bolted to the bicycle’s fork or there is a skewer that passes through the axle (which is basically hollow) and clams it to the fork.

When it comes to bike anatomy, there are two kinds of fork: rigid and suspension. The suspension forks can mostly be found on the mountain bikes and provide travel quite similar to a motorcycle. Rigid forks, on the other hand, are made up of several different materials like Aluminium, Chromoly and Carbon. These generally do not have any travel. This road bicycle component has three different measurements referred to as steerer length, steerer diameter and the wheel clearance.

Saddle: Contact Point #1

saddle bike anatomy
The Anatomy of a Saddle (Source)

In bike anatomy, bicycle saddle is a roadbike component that is also referred to as the seat and is basically one of the three contact points on a bicycle (the other contact points are handlebars and pedals). This saddle is most commonly attached to the seatpost. The height can easily be adjusted with the help of the seatpost that telescopes in and out of the tube of the seat. It has quite a similar role like that of a horse saddle wherein it doesn’t bear the entire weight of the rider. The other contact points also take the load of the rider.

There are several varieties of the saddle. The comfort saddles are quite heavy and are wide as well. They have much more padding in it for extra comfort. The racing saddles, on the other hand, have much lesser padding, are lightweight and are made up of higher-end materials like titanium, exotic alloys and carbon fibre. The saddles for men and women are different too. The women’s saddles are shorter and much wider while the men’s saddles are narrower and longer in length.

Seatpost: The Connecting Tube

bike anatomy seatpost
One Part, Many Names (Source)

The bicycle seatpost, in the bike’s anatomy, is also referred to as saddlepole, seatpin, saddle pin or the saddle pillar. It is basically a tube which connects the saddle to the bicycle’s frame. The seatpost can be made up of carbon fibre, aluminium or steel. Aluminium is the most common material used. The seatpost is inserted into the seat tube so as to attach it to the main frame of the bicycle. The seat tube’s top is squeezed with the help of a tightening ring so as to hold the seatpost in place. This temporarily reduces its diameter.

A vertical slit made of the tube allows it to happen easily without crumbling. It is then that the tube hugs the frame firmly. Also, into the frame, a hole might be created for the binder bolt or the pinch bolt. However, if the hole isn't created, a seatpost clamp of an appropriate size that closely fits the seat tube's diameter can be used.

The size of the seatpost can easily be determined by measuring the post’s diameter. The amount that the seatpost extends out can basically be adjusted. You can find a mark that would indicate the maximum extension or the minimum insertion.

Handlebars: Point of Contact #2

bike anatomy handlebars
Handle With Care (Source)

Another part of a bicycle is known as the bicycle handlebars which refer to the bicycle’s steering mechanism. Other than steering, the handlebars might also support some weight of the rider. These handlebars are also an ideal mounting place for the shift levers, brake levers, bells, cyclocomputers etc. These are generally attached to the fork of the bicycle via the stem.

The handlebars are mostly available in several different styles. The mountain bikes either have the riser or the flat bars. The riser bars sweep up from the stem towards the rider. The flat bars, on the other hand, are completely flat across the bar but rise up towards the rider. The road bike usually comes attached to the drop bars. The drop bars have a flat section along with two hooked areas which drop below the bar’s flat portion. These bars have to be mounted on the road stem.

On the handlebar, you would be able to find the gear levers and the brake. On most of the road bikes these days, these are fused into integrated levers. This can control both the gear selection and the braking. The top of the lever where the rider finds it most convenient and comfortable to rest their hands is referred to as the hoods.

Derailleur: The Controls

In bike anatomy, this is the bike’s transmission system and consists of different sprockets of various sizes. Now, a bike has a front derailleur which is small and a rear derailleur which is large. Both of them have various sprockets which help the chain in rotating. The number of sprockets that a bike has depends on the number of the gears on the bike. The Derailleur can easily be seen and can be worked on for the purpose of maintenance on mountain bikes. However, several urban bikes have internal hub derailleur that remains hidden are quite complex to access.

Rear Derailleur

bike anatomy Rear Derailleur
The Rear Derailleur (Source)

When studying the bike anatomy, you would come across the rear derailleur. The rear derailleur has two main jobs – one of them is to keep the chains tense and the other is to switch the gears. The rear derailleur’s position is adjusted so as to maintain the tension in the chain regardless of what gear you are in. If the chain is in the biggest of the sprocket in front as well as in the back, more amount of chain would be wrapped around the sprocket. This way the derailleur would have to deal with lesser slack. However, in case the chain is in the smallest sprocket both in the front and the rear, the derailleur would have to deal with more slack.

Gear is switched by the rear derailleur by moving the chain’s bottom from side to side. The chain’s top is in tension when you are pedalling the bike. It is here that the chain transmits the force directly from the front sprocket to the rear sprocket. As the chain’s bottom isn’t in too much of tension, the derailleur would be able to move the chain to another sprocket even in a situation when you aren't pedalling too hard.

Front Derailleur

bike anatomy Front Derailleur
Front Derailleur (Source)

The front derailleur, in bike anatomy, is responsible for moving the chain between the front sprockets. It moves the chain’s top part which remains under tension when you are pedalling. This means that you would have to go slow so as to switch the sprockets present in the front. A few front sprockets these days also have been designed cleverly so as to allow the switching of the sprockets even when it is under load.

Brakes: For Stopping in Time

parts of a bicycle
The Types

 

Another essential component that you would come across while studying bike anatomy is the brakes present in the bicycle. The brakes on a bicycle help in reducing the speed or in preventing it from moving further. There are four different types of brakes which can be found on a bicycle: Cantilever, Disc, Caliper (road) and Linear Pull.

  • Cantilever brakes: These brakes can most commonly be found on hybrids, mountain bikes and Cyclocross bikes. These brakes mount on the posts that are located on the fork and the frame. The cable that is attached to it seems like an inverted ‘Y'.
  • Disc brakes: These are generally of two types: mechanical and hydraulic. These types of brakes mounts are placed on the frame near the bottom of the leg of the fork and near the dropouts.
  • Caliper brakes: These can most commonly be found on the road bikes. These mount with a single bolt that is located in the brake’s centre.
  • Linear side-pull: These brakes mount posts similar to the Cantilever brakes. However, with these brakes, the cable, you would notice goes through a tube made up of metal which is attached to one of the brake arms.

Cassettes: The Key to Speed

bicycle components
Cassettes of a Bike (Source)

A bicycle cassette is basically a cluster of sprockets which are attached to the bike’s rear hub. They are firmly held into place with the help of a threaded cassette splines and locking. Depending on the speed of your bike, your bike’s cassette could have anything between 5 to 12 sprockets. Most of the modern bikes these days have 8, 9, 10, or 11-speed cassettes. The gear spreads ranges from 11-21 and all the way up to 12-36 and at times even to 10-42.

Cassettes are important because they offer you a range of gearing options on which your bike’s chain can run on. The gear’s range ratios allow you to vary your pedalling cadence so as to achieve maximum efficiency.

Pedals: Point of Contact #3

bike anatomy
The Mechanics of a Bike (Source)

The bicycle pedal is a bicycle component that the rider pushes with their foot so as to propel the bicycle. It offers the connection between the cyclists' foot and the crank. It allows the leg to turn the spindle of the bottom bracket and thereby propel the wheels of the bicycle. The pedals generally consist of a spindle which threads into the crank’s end and a body on which the footrest is usually attached. This is free to rotate on the bearing with respect to the spindle.

The chain of the drivetrain is engaged by chainrings which have spaced teeth. They come in various sizes and the modern road bikes usually have two to three chainrings. The smaller sized chainrings are used for climbing while the larger chainrings help to generate speed on a flat or downhill section of road.

In a bike’s anatomy, you would notice that there are most commonly two types of pedals: platform (this may or may not have toe clips) and clipless. The platform pedals do not necessarily need a particular kind of cycling shoe to be worn by the rider. The clipless pedals are available with cleats that easily mount onto the cycling shoe's bottom. These cleats come with two bolt patterns for most of the mountain bike shoes.

Originally the pedals were attached to the cranks which connected it directly to the driven wheel which was usually the front wheel. However, these days the pedals are normally attached to the crank driving a sprocket which then transmits power to the driven wheel by the means of a roller chain.

Wheels: What Moves the Bike

anatomy of a bicycle
The Wheels of a Bike (Source)

When talking about bike anatomy, the wheels are also an essential component. The bike wheels are mainly made up of three parts: hub, rim and the spokes. The hub is at the centre onto which the spokes are attached. These are attached to the rim of the wheel. The wheels of the bicycle sit in parts of the fork and the frame which is referred to as dropouts. These are held in place by either the bolt-thru axles or the quick release skewers.

The tires are also an essential component and in most of the cases would have an inner tube present inside them. However, the tubular tires or the tubeless tires can do without the inner tubes completely.

Summing Up

bike anatomy
Know Bike Anatomy, Ride Better

If you want a happy ride all year round, you definitely need to know your bike anatomy. This way you would be able to do the maintenance yourself if required. We really hope that this post helped you to comprehend each and every part of your bike in detail.

Do let us know in the comment section below if this guide helped you in any way.

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