Every part, explained.
Pick a bike part to see what it does, how to spot trouble, and roughly what it costs to fix in the UK.
Drivetrain
6 explainersChain
The metal loop that carries your pedalling power to the back wheel.
Cassette
The stack of toothed rings on your back wheel that gives you different gears.
Chainset (Crankset & Chainrings)
The arms and rings your feet actually push against.
Bottom Bracket
The bearing set the cranks spin on, hidden inside the frame.
Rear Derailleur
The spring-loaded arm that pushes your chain between sprockets.
Front Derailleur
The cage that shoves your chain between chainrings, if your bike has more than one.
Brakes
6 explainersBrake Pads
The friction blocks that grip the wheel or rotor to slow you down.
Disc Rotor
The metal disc bolted to the wheel that the brake pads clamp onto.
Brake Caliper
The clamp that squeezes the pads onto the rim or rotor.
Brake Lever
The handlebar lever your fingers pull to slow down.
Hydraulic Brake Hose
The fluid-filled line that carries braking force from lever to caliper.
Rim Brake (Caliper / V-Brake)
The older-style brake that squeezes pads directly onto the wheel rim.
Wheels & Tyres
6 explainersWheel Rim
The metal or carbon hoop the tyre sits on and the spokes pull against.
Spokes & Nipples
The thin metal rods that hold the rim in tension around the hub.
Hub
The bearing housing at the centre of the wheel that lets it spin freely.
Tyres
The only part of your bike that actually touches the road.
Inner Tube
The rubber ring inside a tyre that actually holds the air.
Tubeless Setup
Running tyres without an inner tube, sealed instead with liquid latex.
Frame & Suspension
6 explainersFrame
The skeleton every other part of the bike bolts onto.
Suspension Fork
The front fork that soaks up bumps instead of transmitting them to your hands.
Rear Shock
The rear equivalent of a suspension fork, on full-suspension bikes.
Headset
The bearings that let your fork, and the handlebars, turn smoothly.
Dropper Seatpost
A seatpost you can raise or lower on the move with a lever.
Quick Release / Thru-Axle
The lever or bolt that clamps your wheel securely into the frame.
Cockpit & Controls
6 explainersHandlebar
The bar you steer with, and where your controls all attach.
Stem
The short tube connecting the handlebar to the fork's steerer.
Grips / Bar Tape
The cushioning your hands actually rest on.
Saddle
The seat — arguably the most personal part of the whole bike.
Seatpost
The tube that holds the saddle at your chosen height.
Gear Shifters
The levers or buttons you press to change gear.
Gears & Shifting
4 explainersGear Cables & Housing
The cable and outer sleeve that carries your shift command to the derailleur.
Derailleur Hanger
A small, deliberately weak bracket that the rear derailleur bolts onto.
Electronic Shifting
Gear changes fired by a button press and a motor, not a cable pull.
Barrel Adjuster
The small dial that fine-tunes gear cable tension without tools.
Electric Bikes
6 explainersE-Bike Motor
The electric motor that adds power to your pedalling.
E-Bike Battery
The pack that stores the energy your motor uses.
E-Bike Controller
The small computer that decides how much power the motor gets.
E-Bike Display / Control Unit
The screen or light-up panel that shows speed, battery and assist level.
Torque Sensor
The sensor that measures how hard you're actually pedalling.
E-Bike Charger
The mains plug-in unit that refills your battery.
Smart Tech
5 explainersBike Computer / GPS
The handlebar-mounted screen that tracks your speed, distance and route.
Bike Lights
Front and rear lights that help you see, and be seen.
Bluetooth Connectivity
The wireless link that connects your bike's electronics to your phone or computer.
Power Meter
A sensor that measures exactly how many watts you're putting out.
Smart Lock
A lock you open with your phone instead of a key.
Comfort & Accessories
5 explainersPedals
Where your feet actually connect to the bike.
Mudguards
The arched shields that stop wheel spray hitting you and your bike.
Pannier Rack
The frame over the wheel that carries bags, without them touching the tyre.
Kickstand
The folding leg that lets your bike stand up on its own.
Bell / Horn
The simple warning device you ring to alert people ahead.