Bicycle glossary of terms used on this website, as well as general cycling terms
Bicycle illustration with basic parts noted can be found in this link: Names of bicycle parts. Clicking an image shows it enlarged. Back browser button to return.
BB: see “Bottom bracket”.
Chainline: distance between the middle of the chainring (or sprocket) set, and the longitudal axis of the bicycle (bikes centerline). Usually measured in mm. Detailed explanation is here: Bicycle chainline.
Chainring: a ring with teeth for engaging the chain. When the term “chainring” is used in cycling, it usually refers to the front chainring. The rear one is usually referred to as “sprocket”, or “cog”.
Crankset: a common cycling jargon misnomer for cranks – it is understood that they come as a set.
FD: see “Front derailleur”.
Head tube angle: Angle of the steering axis – measured compared to the horizontal (another caprice of cycling literature), with both wheels of planned size (usually the same size). In mechanics and engineering literature, this is called “rake”, while in cycling literature, “rake” is used for referring to fork offset.
OLD: Acronym for Over Locknut Distance. Term still used for hub width, although many modern hubs with “industrial” bearings don’t have locknuts. On cup and cone hubs (that used to be the only available in the past), the outer most nuts were used to lock the cones in position by counter-tightening them, so they were called “locknuts”. Explained in this post: Bicycle rear hub.
Pinch flat: see “Snakebite”.
Q-factor: sum of horizontal distances of pedal attachment points of both cranks, from the bicycle’s mid-line. Both distances are ideally identical, while their sum is the Q-factor – how wide are the legs when one stands on the pedals.
Rake: Distance for which the front wheel dropout is moved forward from the head tube axis. Forks are usually angled forward a bit, or have a curve to the front near the bottom. In mechanics and engineering literature this is called “fork offset”, while “rake” is used to refer to what is called “head tube angle” in cycling literature – there are many such misnomers in cycling literature and jargon.
RD: see “Rear derailleur”.
Seatpost: a post (tube) that the saddle is attached to, and which is then inserted into the seat tube.
Seat tube: (almost) vertical tube of the frame that seatpost is placed into. It is marked red in the picture below:
Snakebite: when hitting a kerb, or a rock, if tyre compresses all the way (due to hard impact, and/or low pressure) and pinches the tube against the walls of the rim, creating two small holes, like marks of snake’s teeth. It is also called “pinch flat”.
Sprocket: ring with teeth, for engaging bicycle chain. When a term “sprocket” is used in cycling, it is usually meant the rear one, while the front one is referred to as “chainring”. Of course, a correct technical (engineering) term would be: “rear chainring”. Such misnomers are common in cycling jargon and literature.
Bicycle Glossary by BikeGremlin