bike parts

fork

Usually refers to the front fork, the part of the frameset that holds the front wheel. The fork is attached to the main frame by the headset. The fork consists of the two blades that go down to hold the the axle, the fork crown, and the steerer. The term "rear fork" is sometimes used to refer to the part of the frame that holds the rear wheel.

bottom bracket

The part of the frame around which the pedal cranks revolve, also the bearings and axle assembly that runs through the bottom bracket shell of the frame.

hub

The middle part of a wheel, to which the inside ends of the spokes attach. A hub consists of an axle, which attaches to the forkends; a shell, to which the spokes attach, and bearings to connect the axle to the shell, permitting the shell to revolve around the axle. In the case of a rear hub, the shell would also have a provision for attaching the rear sprocket(s).

rim

The outer metal hoop of a bicycle wheel. The rim does not include the spokes, or the hub.

tire

1. The beads are two hoops of strong steel wire (or, sometimes Kevlar ®.) 2. The cords are cloth, forming the body of the tire, woven between the two beads. Most modern tires use nylon cords. 3. The rubber covers all the other parts. The rubber on the part that contacts the road is thicker, and is called the tread.

tube

A bicycle tire is not airtight by itself, so it uses an inner tube, which is basically a doughnut-shaped rubber balloon. The inner tube has a valve to allow you to blow it up.

cassette

A cluster of sprockets and spacers designed for use on a freehub. Some of the sprockets and spacers may be semi-permanently attached to one another by bolts or rivets.

fender

A covering for the upper part of the wheel, to protect the bicycle and rider from spray when riding in wet conditions. The best fenders run close to the wheels, and cover a large arc. They are supported by wire stays that attach to the fork ends. Short fenders that attach without stays do not give enough protection to be worthwhile.

wheel

A hub, rim, and spokes all together; may also include the tire and tube.

front derailer

A mechanism for moving the chain from one sprocket to another to change gears on a multi-speed bicycle. A typical derailer consists of a parallelogram which moves a cage.

rear derailer

A mechanism for moving the chain from one sprocket to another to change gears on a multi-speed bicycle. A typical derailer consists of a parallelogram which moves a cage. In the case of a rear derailer, the cage has two chain pulleys, a jockey pulley and a tension pulley.

freewheel

A ratchet mechanism that allows the rear sprocket(s) to drive the wheel when pedaled forward, but allows the wheel to turn forward independently even when the sprockets are not turning. normally sold with sprockets attached (cluster). A standard freewheel attaches to a hub by screwing on to external threads that are part of the hub.

chain

Modern bicycles use roller chain to connect the cranks to the rear wheel. Chain size is specified by pitch and width. The pitch is the distance between rollers (1/2" on all modern bicycle chain). The width is the internal width where the sprocket teeth fit in

cable

Most modern bicycles use cables to control the gear shifting and brakes, consist of two parts, an inner cable of twisted or braided steel wire, and an outer cable housing. Cables transmit force by a combination of tension on the inner cable and compression to the housing. in some bikes, housing doesn't run along the full length of the cable, but transmits the compressive part of the load to the frame by means of housing stops, fittings with holes small enough for the cable, but not small enough for the housing to pass through. Some cable stops feature adjusting barrels.

spoke

One of the wires connecting the rim to the hub of a bicycle wheel. A conventional spoke has a swaged head, like the head of a nail, to keep it from pulling through the flange of the hub. Immediately after the head the spoke takes a right-angle bend, also known as the "elbow" of the spoke. The outer end of the spoke is threaded, and a special nut called a nipple fits through the rim and screws onto the spoke threads. Most wheels have 32-40 spokes

quick release skewer

Quick-Release wheels use a cam mechanism to allow the wheels to be removed quickly, and without any tools. As the quick-release lever is rotated from the open to the closed position, the cam built into the pivoting end of the handle applies a push to the quick-release mechanism housing, and a pull to the skewer.

crank

The arm which connects the pedal to the bottom bracket axle.

chain stay

The (usually tapered) tubes that run from the bottom bracket to the rear fork ends.

seat post binder bolt

The binder bolt that secures the seat post in the frame. It may be a conventional bolt with a nut, or an Allen bolt, or a quick release.

cable guide

The cable guide is attached to tubes and guides the cable to either the derailers or brakes

seat tube

The frame tube running from the bottom bracket up to the seat cluster.

down tube

The frame tube that runs diagonally up from the front of the bottom bracket up to the lower end of the head tube.

head tube

The front tube of the frame, through which the steerer passes. The length of the head tube gives a quick visual indication of frame size, because it varies more, proportionally, with frame size than any of the other tubes.

handle bars

The handle bars holds the grips, shifters and brake levers. it attaches to bike with the stem and is what you hold on to when riding your bike

valve stem

The part of the inner tube that permits air to be added. There are three types used on bicycles, Presta(high performance bicycles and tubulars), Schrader(automotive-children's and utility bicycles), and Woods(rare in us)

pedal

The part you put your foot on. The axles of the pedals screw into the cranks. The right pedal has a normal thread, but the left pedal has a left (reverse) thread.Most pedals have 9/16" x 20 tpi threads.

seat post

The tubular support that holds the saddle. The seatpost telescopes into the seat tube of the frame, providing the adjustment for saddle height. It is usually secured by a pinch bolt at the top of the seat tube.

front light

a light usually attached to the handle bars or stem to keep you visible while on the road

rear light

a light usually attached to the seat tube or seat post to keep you visible while on the road

shifter

lever or twist-grip on handlebars or head tube that controls the gear shifting system (derailleur or internal hub)

brake lever

levers/handles that are used with cable operated brakes, come in 4 basic types, the differences depend on the handlebar type they are used with and the amount of cable travel required

upright handlebar

more common, more comfortable for cyclists who ride at low intensity levels

saddle

not intended to support riders full wait, leather stretched over metal frame or plastic with gel/closed cell foam as a cushion

rack

rack that allows a rider to carry more items.

reflector

reflects light and can be found on the spokes, fenders and instead of lights on the front and back.

headset

the bearing assembly that connects the front fork to the frame and allows the fork to turn for steering/balancing purposes

top tube

the frame that runs horizontally from the top of the head tube to the seat cluster. until 1980s higher end top tubes were built entirely horizontal, but newer frame designs have sloping top tubes that are higher at the front. (common in smaller frame sizes) probably most important dimension in providing a comfortable fit.

grips

the grips are what you hold on to when riding they are attached to the handle bars.

stem

the part of the bike that connects the handlebars to the steerer of the fork

seat stay

the thin frame tubes that run from the rear forkends up to the seat cluster