Parts of a Bike Frame – Labeled Diagram with Names

All 19 parts on the diagram

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The frame 12

Top tube It joins the head tube to the top of the seat tube. It can be level or slope down toward the seat.
Down tube It joins the head tube to the bottom bracket shell.
Seat tube The seatpost slides into its top. At the bottom it joins the bottom bracket shell.
Head tube It holds the headset, the bearings the fork's steerer tube turns in.
Seat stays There is one on each side of the wheel. From the side they look like one. They end at the rear dropouts.
Chain stays They run beside the chain. They go from the bottom bracket shell to the rear dropouts.
Bottom bracket shell The seat tube, down tube and chain stays all meet here. The axle the cranks turn on runs through it.
Lugs On a classic steel frame each tube end fits inside a lug. It is brazed to the lug. Welded frames have no lugs.
Binder bolt Tightening it pinches the seat tube round the seatpost. The saddle then stays at its height. It is also called a pinch bolt.
Bottle cage mounts A water bottle cage bolts onto each pair.
Cable stops A cable's outer housing ends at a stop. The bare inner cable carries on through the hole.
Pump peg It holds one end of a tire pump carried on the frame.

Dropout and fork 7

Dropouts The slot lets the wheel out without taking the chain off first. The seat stay and chain stay on each side end here.
Derailleur hanger The rear derailleur bolts into its threaded hole. On many newer frames it is a separate piece that can be replaced.
Eyelets A fender or a rack bolts on here.
Steerer tube It goes up inside the head tube. The headset's bearings let it turn there. The handlebar stem fastens to it.
Fork crown The steerer tube rises from the top of it.
Fork blades From the side they look like one. They taper and curve forward toward the wheel's axle.
Fork ends The front wheel's axle sits in them.

How this list was compiled: Part names checked on 2026-09-30; a name is kept only when two independent sources use it. (1) Wikipedia, text only: Bicycle frame (diamond frame, main triangle and rear triangle, head tube, top tube, down tube, seat tube, chain stays, seat stays, bottom bracket shell, lugs, a bridge between the seat stays), Bicycle fork (blades, fork crown, steerer tube, fork ends), Fork end (dropout, derailleur hanger below the axle, eyelet above it), Braze-on (water bottle cage mounts, cable guides and stops, pump pegs), Seatpost (pinch bolt or binder bolt, seatpost clamp), List of bicycle parts. (2) Sheldon Brown's Bicycle Glossary, https://www.sheldonbrown.com/glossary.html and its lettered pages (top tube, down tube, seat tube, head tube, seat stays, chainstays, bottom bracket shell, dropouts and fork ends, derailer hanger, eyelets for fenders and racks, lugs, binder bolt, braze-ons: cable stops and guides, water bottle cage mounts, pump pegs; fork blade, fork crown, steerer). Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's frame, nothing traced. Licence: own work

How it works

The parts of a bike frame are mostly tubes, and each tube has a name. This is a road bike frame with nothing fitted to it, and the fork is drawn out of the frame so its top shows.

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Two triangles

The parts of a bicycle frame make a diamond. The main triangle is the head tube, top tube, down tube and seat tube. The rear triangle is the seat tube again with the seat stays and chain stays, which meet at the dropouts. Everything low down joins at the bottom bracket shell.

The small fittings, and the fork

Lugs sleeve the joints of this steel frame. Cable stops, bottle cage mounts and a pump peg are fixed to the tubes. The second view shows the dropout with its derailleur hanger and eyelet, and the fork: steerer tube, crown, blades and fork ends.

The bottom bracket shell is part of the frame. The bottom bracket is the set of bearings and the axle that fit inside it.
Only a frame joined with lugs has lugs. On a welded or molded frame the tubes meet directly.

Questions and answers

What are the parts of a road bike frame called?

Head tube, top tube, down tube and seat tube make the main triangle. Seat stays and chain stays make the rear triangle and end at the dropouts. The bottom bracket shell joins them at the bottom, and the fork sits in the head tube.

What is the difference between seat stays and chain stays?

Both are pairs of thin tubes that run to the rear wheel. Seat stays come down from the top of the seat tube. Chain stays run back from the bottom bracket shell, beside the chain.

What is a dropout on a bike frame?

A slotted plate at the end of the stays that holds the rear wheel's axle. The slot lets the wheel drop out without taking the chain off. The same kind of slot at the bottom of the fork is a fork end.

Is the fork part of the bike frame?

Not strictly. A frame and fork are often made and sold as a pair, called a frameset, but the fork is a separate part. Its steerer tube turns inside the frame's head tube.