This question and its answers list the names of bike parts and cycling concepts.

Some Rules
----------

* Make sure you only put one term per answer!
* Try to include an image if applicable
* Include sources that contain detailed information
* Add a link to the index in this question using edit.

Also, I made this a community wiki, so that anyone will be able to edit it, and to stop rep-hoarding

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There's a handy reference at the [Park Tool Co. website](http://www.parktool.com/), a bike repair map; it's a diagram of a bike with all the parts labeled, and is very handy! At the moment, the diagram is up at [parktool.com/blog/repair-help](http://www.parktool.com/blog/repair-help). (They've changed the URL in the past, so this link may break.)

A road bike has the following parts ([source](http://www.jimlangley.net/wrench/wrench_images/bicycle_parts_labeled.jpg)):

[![enter image description here](https://i.stack.imgur.com/idu5B.jpg)](https://i.stack.imgur.com/idu5B.jpg)

A mountain bike has the following parts ([source](https://upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Bicycle_diagram-en.svg/850px-Bicycle_diagram-en.svg.png)):
[![enter image description here](https://i.stack.imgur.com/Ab4v5.png)](https://i.stack.imgur.com/Ab4v5.png)

---

**Edit**: This page is meant to identify what things or concepts are (as per [this thread in meta](https://bicycles.meta.stackexchange.com/questions/80/glossary-threads)). If you want to recommend an accessory or a specific product you've found handy, please use the [accessories page](https://bicycles.stackexchange.com/questions/573/whats-your-most-useful-cycle-accessory).

---

| **Contents** |  |
| --- | --- |
| [Actuation Ratio](https://bicycles.stackexchange.com/a/84691)[Axle](https://bicycles.stackexchange.com/a/62590/32314) | [Axle Nuts](https://bicycles.stackexchange.com/a/42804/) |
| [BCD (Bolt Circle Diameter)](https://bicycles.stackexchange.com/a/55802/32314)[Bearing](https://bicycles.stackexchange.com/questions/244/terminology-index/2758#2758)Belt Drive[Bidon/Bottle](https://bicycles.stackexchange.com/a/64385/)[Bonk/Bonking](https://bicycles.stackexchange.com/a/42193/)[Bottle Cage / Bottle Holder](https://bicycles.stackexchange.com/a/13051/32314)[Bottom Bracket](https://bicycles.stackexchange.com/questions/244/terminology-index/2759#2759) | [Boom/Boom Tube](https://bicycles.stackexchange.com/a/74190/)[Brazed Frame](https://bicycles.stackexchange.com/a/37137/7044)[Brifter](https://bicycles.stackexchange.com/questions/244/terminology-index/6918#6918)[BSD (Bead Seat Diameter)](https://bicycles.stackexchange.com/a/67892/38558)[BSO/Bike-Shaped-Object](https://bicycles.stackexchange.com/questions/244/terminology-index/887#887) |
| [Cable Pull](https://bicycles.stackexchange.com/a/20810/7044)[Cable Stretcher](https://bicycles.stackexchange.com/questions/244/terminology-index/667#667)[Cadence](https://bicycles.stackexchange.com/questions/244/terminology-index/451#451)[Cassette](https://bicycles.stackexchange.com/questions/244/terminology-index-a-list-of-bike-part-names-and-cycling-concepts/82208#82208)[Chain](https://bicycles.stackexchange.com/a/82263/48599)[Chainline](https://bicycles.stackexchange.com/a/85714/48599)[Chain Gauge](https://bicycles.stackexchange.com/questions/244/terminology-index/2793#2793)[Chain Guard/Cover](https://bicycles.stackexchange.com/a/21177/8)[Chain Tool](https://bicycles.stackexchange.com/questions/244/terminology-index/3480#3480)[Chain Tug/Chain Tensioner](https://bicycles.stackexchange.com/questions/244/terminology-index/3042#3042) | [Chainstay Length](https://bicycles.stackexchange.com/questions/244/terminology-index/4477#4477)[Chainsuck](https://bicycles.stackexchange.com/a/56029/32314)[Chamois](https://bicycles.stackexchange.com/questions/244/terminology-index/5154#5154)[Clipless Pedals](https://bicycles.stackexchange.com/questions/244/terminology-index/245#245)[Coaster Brake (foot brake / pedal brake)](https://bicycles.stackexchange.com/a/62698/32314)[Crank](https://bicycles.stackexchange.com/questions/244/terminology-index/3157#3157) |
| [Derailleur](https://bicycles.stackexchange.com/questions/244/terminology-index/64473#64473)[Derailer Hanger/Derailleur Ranger](https://bicycles.stackexchange.com/questions/244/terminology-index/3665#3665)[Detangler](https://bicycles.stackexchange.com/a/82979/19705)BMX Direct DriveDisk/Disc Brake[Disc Hub](https://bicycles.stackexchange.com/questions/244/terminology-index/4425#4425) | [Door Zone](https://bicycles.stackexchange.com/questions/244/terminology-index/1602#1602)[Dropout](https://bicycles.stackexchange.com/a/23046/8273)[Dropper Post](https://bicycles.stackexchange.com/questions/244/terminology-index-a-list-of-bike-part-names-and-cycling-concepts/64406#64406)[Dunlop Valve](https://bicycles.stackexchange.com/questions/244/terminology-index/1417#1417) |
| e  Engine/Motor | Electronic shiftingEccentric |
| [Fender/Mudguard/Mudflaps](https://bicycles.stackexchange.com/questions/244/terminology-index/2803#2803)[Fixed-Gear](https://bicycles.stackexchange.com/questions/244/terminology-index/271#271)[Flip-Flop Hub](https://bicycles.stackexchange.com/questions/244/terminology-index/1982#1982)[Folding Bike](https://bicycles.stackexchange.com/questions/244/terminology-index/263#263)Fork | [Foot Peg](https://bicycles.stackexchange.com/a/82982/19705)[Frame](https://bicycles.stackexchange.com/questions/244/terminology-index/5583#5583)[Frame Sizing](https://bicycles.stackexchange.com/a/81667/38270) |
| [Gear Inches](https://bicycles.stackexchange.com/questions/244/terminology-index/1863#1863) | [Groupset](https://bicycles.stackexchange.com/questions/244/terminology-index/7787#7787) |
| [Handlebars](https://bicycles.stackexchange.com/questions/244/terminology-index/322#322)[Headset](https://bicycles.stackexchange.com/a/10078/4239)[Hose Clamp aka Jubilee Clip](https://bicycles.stackexchange.com/questions/244/terminology-index/571#571) | [Hub](https://bicycles.stackexchange.com/questions/244/terminology-index/3404#3404)[Hub Skewer](https://bicycles.stackexchange.com/questions/244/terminology-index/4478#4478) |
| [Internally-Geared Hub](https://bicycles.stackexchange.com/questions/244/terminology-index/1728#1728) |  |
| j |  |
| [Keel Tube](https://bicycles.stackexchange.com/a/74186/) |  |
| [Lawyer lips/lawyer tabs](https://bicycles.stackexchange.com/questions/244/terminology-index/5584#5584)[Lateral Tube](https://bicycles.stackexchange.com/a/74187/)[LBS/Local Bike Shop](https://bicycles.stackexchange.com/questions/244/terminology-index/254#254) | [Lights](https://bicycles.stackexchange.com/a/81756/)[Luggage Carrier/Rack](https://bicycles.stackexchange.com/questions/244/terminology-index/1862#1862)[Lugged Frame](https://bicycles.stackexchange.com/a/37138/) |
| [Master Link](https://bicycles.stackexchange.com/questions/244/terminology-index/4483#4483)[MIPS](https://bicycles.stackexchange.com/a/81693/) | [Mixte](https://bicycles.stackexchange.com/questions/244/terminology-index/4539#4539)[Mountain Bike](https://bicycles.stackexchange.com/a/13057/8) |
| nNoodle |  |
| o[Over Locknut Dimension or OLD](https://bicycles.stackexchange.com/a/83206/48599) |  |
| [Pannier](https://bicycles.stackexchange.com/questions/244/terminology-index/402#402)[Play](https://bicycles.stackexchange.com/a/58543/)[Potts Mod](https://bicycles.stackexchange.com/a/82978/19705) BMX Brakes[Power Meter](https://bicycles.stackexchange.com/a/7175/8) | [Presta Valve/Presta Tube](https://bicycles.stackexchange.com/questions/244/terminology-index/283#283)[Pump Peg](https://bicycles.stackexchange.com/a/37145/) |
| [Q-Factor](https://bicycles.stackexchange.com/a/64382/) | [Quick-Release](https://bicycles.stackexchange.com/questions/244/terminology-index/404#404) |
| [Recumbent Cycles](https://bicycles.stackexchange.com/a/81883/38270)[REI (Recreational Equipment Inc)](https://bicycles.stackexchange.com/a/41694/32314)[Rim](https://bicycles.stackexchange.com/questions/244/terminology-index/825#825) | [Rim Tape](https://bicycles.stackexchange.com/a/59097/24228)[Rim Brakes, e.g. cantilever, dual pivot, V-brakes](https://bicycles.stackexchange.com/a/81822/38270)Rotor |
| [Saddle](https://bicycles.stackexchange.com/questions/244/terminology-index/2812#2812)[Saddlebag](https://bicycles.stackexchange.com/questions/244/terminology-index/403#403) [Schrader Valve/ Schrader Tube](https://bicycles.stackexchange.com/questions/244/terminology-index/284#284) Shaft Drive [Single-speed](https://bicycles.stackexchange.com/a/35893/32314) [Skewer](https://bicycles.stackexchange.com/questions/244/terminology-index/4478#4478) | [Spider](https://bicycles.stackexchange.com/a/22974/8273)[Spoke](https://bicycles.stackexchange.com/a/13056/8)[Stack and Reach](https://bicycles.stackexchange.com/a/83416/48599)[Stay, Mudguard/fender](https://bicycles.stackexchange.com/a/81592/19705)[Stem](https://bicycles.stackexchange.com/questions/244/terminology-index/270#270)[Suspension Fork/Rear Shock](https://bicycles.stackexchange.com/a/64405/38558) |
| [Through/Thru Axle](https://bicycles.stackexchange.com/a/41723/)Tire, ClincherTire, Tubeless Tire, TubularTire, Solid/airless/runflat[Tire Boot](https://bicycles.stackexchange.com/a/81940/)[Tire Clearance](https://bicycles.stackexchange.com/a/44014/)[Tire Lever/Tire Iron](https://bicycles.stackexchange.com/questions/244/terminology-index/1960#1960) | [Tire Saver](https://bicycles.stackexchange.com/a/22938/7044)Tire Sealant[Tolerances](https://bicycles.stackexchange.com/a/81703/38270)[Track Pump/Floor Pump](https://bicycles.stackexchange.com/questions/244/terminology-index/2792#2792)[Triathalon Bars/Triathlon Bars](https://bicycles.stackexchange.com/questions/244/terminology-index/260#260) |
| uU-Brake |  |
| V-Brake[Velomobile](https://bicycles.stackexchange.com/a/81885/19705) |  |
| [Welded Frame](https://bicycles.stackexchange.com/a/37139/7044) |  |
| x |  |
| y |  |
| z |  |