Parts of a Bike Diagram: Bicycle Anatomy for Beginners
In the bike parts diagram above, I've labelled some of the most important bicycle components. If you can't find what you're looking for, scroll down, as I go into more detail below!
I've tried to keep all the information short and sweet, as this is more of a beginners guide to bike anatomy than some exhaustive technical encyclopaedia.
However, it's really useful to at least know the names of the parts of your bike, as it helps when you're describing problems and you’ll know what I'm on about when I'm explaining the best ways to lock a bike etc!
Bike Frame Parts
The frame is the rigid heart of a bike. Traditionally bike frames were made from steel. But these days they're mostly made from aluminium alloy. However, carbon fiber and titanium are used on high end bikes. Frames need to be strong, light and stiff.
A frameset is the frame combined with the fork.
The most common style of frame is the diamond frame which is made up of 6 tubes fashioned into two connected triangles...
The top tube is also known as the cross-bar and it’s the one you step over to mount the bike! Usually it runs parallel to the ground, but it may be slightly angled. And some bikes have very steeply angled or no top tubes to make it easier to get on and off the bike.
The head tube is the short tube at the front of the frame, which connects the handlebars to the wheel fork. It contains the headset which allows us to steer the front wheel via the handlebars!
The down tube is the long tube that runs from the head tube (just below the handlebars), down to the pedals. It’s usually the thickest part of the frame. It's where you’ll find the cage for carrying a water bottle and the logo of the bike brand!
The seat tube runs from beneath the saddle down to the pedals. The seat post is inserted into the top of the seat tube. The height of the saddle is adjusted by increasing or decreasing how deep the seat post descends into the seat tube.
The seat stays are two thinner tubes that run from underneath the saddle, down to the rear wheel hub. Each seat stay ends at a "rear drop out". And each rear drop out is connected to one side of the axle of the rear wheel.
The chain stays are two thinner tubes which run parallel to the ground, from either side of the pedals to either side of the rear wheel. They run alongside the bike chain, which is why they’re called chain stays!
Front of the Bike Parts
This is my unofficial name for all the bike parts that are at the front of the bike! It includes:
The fork connects the front wheel to the frame. At the bottom, the fork blades extend downwards from the head tube, one on each side of the wheel. At the top of the fork, hidden inside the head tube, is the steerer tube, which connects to the headset.
The headset is a set of components that sit inside the head tube and connect the frame and the wheel fork. Bearings in the headset allow it to rotate so that a turn of the handlebars produces a turn of the front wheel.
The stem is the bike part that connects the steerer tube of the fork to the handlebars. Essentially it’s the bit that sticks out forwards from the top of the head tube. The handlebars run through the end of the stem.
The handlebars are what you use to steer the bike! There are connected to the frame via the stem. Flat handlebars are used on mountain bikes, hybrids and urban bikes. Drop handlebars are used on road bikes. But there are many other styles too.
Brake levers are the parts of the bike that you squeeze to slow down! Sometimes they're combined with a gear shifter to become a “brake shifter” also known as a “brifter”. Brake cables emerge from the brake levers and pass down the frame to the actual brakes on the wheels.
Brakes (Rim vs Disc)
There are two widely used types of bicycle brakes: rim brakes and disc breaks. Rim breaks (so called because they are applied to the wheel rim), are the most common as they're light, cheap, easy to maintain and powerful. However they don't work so well in wet conditions.
Disc breaks are applied to a special metal disc that's attached to the wheel hub. They work better in wet conditions and are more robust than rim brakes. Although they're most commonly seen on mountain bikes, they're increasingly used on all types of bicycle.
Bike Wheel Parts
I hope we already know what the wheels are. There are usually two (together called a wheelset). But on trikes you’ll find three. Each wheel is made up of several other bike parts though…
The hub is in the centre of the bike wheel. It’s made up of 3 parts: the hub shell, the bearings and the axle.
The hub shell is the exterior part that the spokes attach to. The axle is the bar that protrudes on either side, and that attaches to the frame. And the bearings sit between the axle and the shell, allowing the shell to spin freely around the axle.
The rim is the circle of metal that forms the outside of the wheel. Rims used to be made from steel, but since the 1980s they’re usually made from aluminium alloy. If they’re to be used with rim brakes, there is a smooth surface on the side for the brake pads to grip.
The spokes connect the rim to the hub. They apply tension evenly in all directions, which creates a strong and stable wheel that’s able to support your weight and the force you apply when you pedal. Where the spokes meet the rim, there are nuts called nipples which are used to adjust the tension.
The tire is mounted onto the wheel rim and provides the interface between the bike and the road surface. Tires are made from rubber impregnated cloth with a thicker rubber outer layer for tread. The tire fits over an air filled inner tube which provides suspension.
Valve (Schrader vs Presta)
Air is added to, or expelled from the inner tube by a valve which sticks out through a hole in the wheel rim. There are two commonly used types of valve: Schrader and Presta. Schrader valves are also used on cars and motorbikes. While Presta valves are only used on bicycles!
Back of the Bike Parts
This is my unofficial name for all the bike parts that are at the back of the bike! It includes:
Crankset / Chainset
The crankset is the part of the bike that your legs push around, in order to turn the rear wheel. It consists of the chainrings (which the chain goes round), and the crank arms (which the pedals attach to).
The chainrings are the front gears of the bike. On a single speed bike there’s only one chain ring. On a geared bike there will be up to 3.
The crankset is attached to the frame by the bottom bracket, to the rear wheel by the chain and to you, the rider by the pedals!
The pedals are the spinning interface between your feet and the bike. You push down on them to move forward!
There are broadly two types of pedal: flat/platform pedals which you simply rest your feet on top of, and clip-in pedals that you use with special shoes that have cleats in the soles to attach them to the pedal more securely.
The bottom bracket is the part of the bike that the crank arms rotate around. It consists of a spindle (which the crankset attaches to), and bearings (which allow the smooth rotation of the spindle). The bottom bracket slots into the bottom bracket shell at the base of the frame.
The bike chain is the part that transfers the power of your legs to the rear wheel. It loops around the chainrings in the crankset, along the length of the chain stay and around the sprockets of the cassette in the rear wheel.
The front derailleur is the part of the bike that moves the chain from one chainring to the other as you shift gears. So it will only be present on bikes with more than one front gear (more than one chainring).
Cassette / Cogset
The cassette is a stack of different sized sprockets (or cogs) that is attached to the hub of the rear wheel. The cassette cogs are the rear gears of the bike. So if your bike doesn’t have any gears, there will only be one cog.
The rear derailleur is the bike part that moves the chain from one cassette cog to another on the rear wheel when you shift gears. It works in conjunction with the jockey wheel. The rear derailleur will only be present if your bike has gears!
The jockey wheel maintains tension in the chain and keeps it moving smoothly as you change gear. If your bike doesn’t have gears, it's unlikely to have a jockey wheel unless it’s being used as a chain tensioner on a single speed bike.
Bike Seat Parts
The saddle is the part of the bike that you sit on! There are lots of different shapes and sizes of bike saddle. They all have saddle rails on the underside, which are used to connect the saddle to the seat post via a saddle clamp.
The seat post is inserted into the seat tube and is moved up and down to adjust the height of the saddle. It is kept in place by tightening a seat post clamp that sits around the very top of the seat tube, so that it squeezes the seat tube against the seat post.
More Good Stuff:
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Last Updated on July 3, 2021 by Carl Ellis
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