A modern bicycle has roughly 50–60 distinct parts, organized into seven systems: the frame and fork; the wheels (rim, hub, spokes, tire, tube); the drivetrain (chain, cassette, chainrings, derailleurs, shifters); the brakes (calipers, levers, rotors or rim); the cockpit (handlebars, stem, headset, grips); the contact points (saddle, seatpost, pedals); and the electronic systems (on e-bikes and Di2/AXS-equipped bikes). This hub explains every part, why it matters, and how to spec it correctly when buying or upgrading.

Drivetrain

The drivetrain is the system that converts your pedaling into forward motion: chainrings (front), cassette (rear), chain, and the derailleurs and shifters that control which gear is engaged.

• Bike drivetrain explained
• Bike cassette: tooth counts, freehub bodies, and replacement
• How bike gears work
• microSHIFT vs Shimano — budget drivetrain comparison
• SRAM vs Shimano — the big-two compared
• Internal gear hubs explained

Wheels and tires

• All the parts of a bike wheel — hub, spokes, rim, tire, tube
• Quick-release wheels explained
• Bike axle types and standards
• Bike rim width to tire size chart
• Bike inner tube size chart
• Folding-bead vs wire-bead tires
• What is tire clearance?

Cockpit: handlebars, stem, and contact points

• Flat bars vs drop bars
• How to choose road bike handlebars
• How to raise bike handlebars
• Bicycle seatpost sizes & materials
• Bike dropouts and fork ends explained

Pedals and cleats

• Clipless pedals vs flats
• Clipless bike pedals: complete guide
• How to install and adjust cleats
• What is Q-factor?

Sizing, fit, and measurement

• How to measure inseam for bikes
• How to choose the right bike size

This is a living index — we add new parts explainers monthly. If a specific component isn’t covered yet, the broader Bike Maintenance Guides hub probably has it under a how-to.