• 26 parts
  • Checked September 2026

Parts of a BMX Bike Diagram

A freestyle BMX bike from the side, then its bars, stem and detangler from the front.

Parts of a BMX Bike Diagram

Name Date

Tap any part to read, rename or leave it out

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
More options

Write the name of each numbered part.Answer key

  1. Seat
  2. Tires
  3. Pedals
  4. Chain
  5. Handlebars
  6. Grips
  7. Fork
  8. Pegs
  9. Top tube
  10. Down tube
  11. Seat tube
  12. Seat post
  13. Crank arms
  14. Sprocket
  15. Rims
  16. Spokes
  17. Brake lever
  18. Stem
  19. Crossbar
  20. Chain stays
  21. Seat stays
  22. Bottom bracket
  23. Freewheel
  24. U-brake
  25. Headset
  26. Detangler

Drawn for this site on 2026-09-30 from plain geometry, a composite of no one make. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: a bike wheel, hub to tire

All 26 parts on the diagram

Show the list

Frame and seat 7

  1. Seat It is fixed to the top of the seat post.
  2. Top tube It joins the head tube to the seat tube at the top.
  3. Down tube It joins the head tube to the bottom bracket.
  4. Seat tube The seat post slides into its top.
  5. Seat post It slides into the seat tube. A binder bolt clamps it.
  6. Chain stays They join the bottom bracket to the rear axle.
  7. Seat stays They join the top of the seat tube to the rear axle.

Pedals and chain 6

  1. Pedals Each pedal screws into the end of a crank arm.
  2. Chain It carries the pedals' push from the sprocket to the back wheel.
  3. Crank arms On three-piece cranks the two arms bolt onto a separate spindle.
  4. Sprocket Also called the chainwheel or chainring; the chain runs round it.
  5. Bottom bracket It sits where the seat tube, down tube and chain stays meet.
  6. Freewheel Like the chain, it must be kept clean and oiled.

Wheels, brake and pegs 5

  1. Tires BMX tires are thick and fat, to absorb shocks.
  2. Pegs Riders use them to grind along or balance on rails and ledges.
  3. Rims The brake pads press on the rim to slow the wheel.
  4. Spokes They must all be tight, with none broken.
  5. U-brake Its two arms pivot on the frame. They squeeze pads onto the rim.

Bars and front end 8

  1. Handlebars BMX bars rise higher than straight bars.
  2. Grips They must sit tight on the bars, with the bar ends plugged.
  3. Fork Its top turns inside the head tube, in the headset.
  4. Brake lever Squeezing it pulls a cable to the brake at the back wheel.
  5. Stem It clamps the bars and fixes them to the fork's steering tube.
  6. Crossbar It braces the tall bars to make them stiff and strong.
  7. Headset Its bearings let the fork turn smoothly in the frame.
  8. Detangler It lets the bars spin fully round without tangling the brake cable.

How this list was compiled: Part names checked on 2026-09-30, a name kept only when at least two of these use it. (1) Schwinn, BMX, Freestyle and other Single Speed Bicycles Owner's Manual, parts identification for BMX bicycles (brake lever, handlebar, grip, seat, seat post, stem, head set, top tube, down tube, seat tube, seat stay, chain stay, chain wheel, crank arm, pedal, rim, freewheel, detangler, pegs, crossbar), full text at https://archive.org/details/manualzilla-id-6982418. (2) Shaun White Supply Co. BMX owner's manual, bicycle parts diagram (seat tube, top tube, down tube, seat stay, chain stay, handlebar, stem, head set, front fork, seat, seat post, rear brake, U-brake, rotor or detangler, spokes, rim, tire, freewheel, bottom bracket, chain wheel or sprocket, crank arm, pedal, front and rear peg, chain, crossbar), full text at https://archive.org/details/manualzilla-id-7349021. (3) Diamondback BMX owner's manual (brake rotor, chainring, handlebar grips and plugged bar ends), full text at https://archive.org/details/manualsbase-id-638958. (4) Wikipedia, text only: BMX bike, Detangler, Bicycle frame, Bicycle handlebar, Bicycle brake (U-brakes), Crankset, Bottom bracket, Stem and Headset. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry, a composite of no one make; nothing traced. Licence: own work

How it works

A BMX bike is a small, sturdy bicycle for racing and stunt riding: one gear, thick tires and tall handlebars. These two drawings name 26 of its parts, from the top tube to the pegs.

Read the full guide

Two drawings

The first shows the whole bike from the chain side: the frame tubes, the seat, the pedals and chain, and the wheels. The second shows the front end from the front, drawn larger than life so the stem, detangler and headset can be told apart.

The frame, tube by tube

The top tube and the down tube both start at the head tube, where the fork turns. The down tube ends at the bottom bracket, between the pedals. The seat tube rises from there to the seat post. Two pairs of thinner tubes run back to the rear axle: the seat stays from under the seat and the chain stays from the bottom bracket.

  • Sprocket, chainwheel and chainring are three names for the same toothed wheel at the pedals.
  • Not every BMX bike has every part: many street riders fit no brake at all, so no lever, cable or detangler.

Questions and answers

What are the parts of a BMX bike called?

The frame (top tube, down tube, seat tube, seat stays and chain stays), the fork, stem and handlebars, the seat and seat post, the cranks, sprocket, chain and freewheel, and two wheels, often with pegs on the axles.

What is a detangler on a BMX bike?

A detangler, also called a gyro or rotor, sits under the stem. The brake cable splits in two and joins its plates, so the handlebars can spin all the way round without tangling the cable.

What are the pegs on a BMX bike for?

Pegs are short tubes fixed over the ends of the axles. Riders use them to grind along or balance on rails, ledges and other obstacles.

What is the sprocket on a BMX bike?

The large toothed wheel at the pedals. The cranks turn it, and the chain carries that turn to the freewheel on the back wheel. Owner's manuals often call it the chainwheel.

Do BMX bikes have brakes?

Race bikes are required to have them. Freestyle bikes often have one U-brake at the back wheel, and many street riders fit no cable brake at all.

More quizzes

Show 6 more

Browse Science Quizzes