How bicycles are made
There are more than a billion bicycles, and the basic diamond-frame design has barely changed since 1885.
- stations
- 8
- things upstream
- 88
- raw sources
- 26
- steps from the ground
- 10
The short version
A bicycle is a welded frame of steel, aluminum or carbon fiber tubes, two wheels, and a chain drive. Tubes are cut and joined, the frame painted, and wheels are laced with steel spokes. Workers then add the chain, gears, brakes and handlebars, and tune the machine before it is boxed.
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Cut the frame tubes
Tubes are cut to length and mitered to fit one another. Many are butted, meaning the walls are thicker at the ends where the stress is highest.
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Join the triangles
Tubes are welded or brazed into a front triangle of head tube, top tube, down tube and seat tube, with a rear triangle behind it. Carbon frames are instead laid up in resin.
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Paint the frame
Frames are cleaned, primed and painted, usually in a baking oven, then covered with a clear coat and decals.
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Lace the wheels
Steel spokes are threaded from the hub to the rim and tightened until the wheel is true and round.
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Mount the tires
A tire and an inner tube, or a tubeless sealing system, are put on each rim and inflated.
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Fit the drivetrain
Pedals turn the cranks and chainring. A chain carries power to the rear sprockets, and a derailleur shifts it between them to change gear.
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Add brakes and cables
Brake calipers, levers and cables or hoses are fitted, along with handlebars, saddle and seat post.
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Tune and test
A mechanic adjusts the gears and brakes and checks the wheels, then rides the bicycle or spins it on a stand before it is boxed.
Worth repeating
- By the early 21st century there were more than 1 billion bicycles in the world.
- Alloy steels came into use for better frames in the late 1930s, and aluminum welding techniques improved enough by the 1980s for aluminum frames to become common.
- Most bicycles use a derailleur system, with 5 to 12 sprockets on the back wheel and two or three chainrings at the pedals.
Back to the ground
Follow every input upstream and bicycle starts as these 26 raw sources.
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Sources
Cite this page: "How bicycles are made." Assembly Line, 2026-11-03. https://assemblyline.org/make/bicycle