Glossary of Major Parts:
A layman's guide to help you out at the bike shop.
Drivetrain: All of the components that are involved in the bicycle’s gear system. Basically, these are the parts that make your bicycle go.
Front Derailleur: The mechanism that shifts the chain from one chainring to another. Located near the chainrings, it usually attaches to the seat tube of the bicycle frame and is controlled by the left hand shifter.
Rear Derailleur: The mechanism that shifts the chain from one cassette to another, making incremental changes to make pedaling easier or harder. Attached to the rear of the bike and is controlled by the right hand shifter.
Chainring: The sprockets attached to the crank of the bike. Mountain bikes generally have 3, though systems with 2 chainrings are becoming more common on high end racing type bikes. Road racing bikes have 2 chainrings. Some commuter bikes and most beach cruisers have one chainring.
Cassette: The sprocket that attaches to the rear wheel of the bike. Each individual sprocket on the cassette is considered a gear. Common cassettes can have anywhere from 5 to 11 gears, depending on the purpose and price of the bicycle. Generally, the more expensive the bike, the more gears it has.
Bottom Bracket: The bearing and axle system that attaches the cranks to the bicycle and allow them to turn freely while pedaling. There are many different types of bottom brackets, but they all perform the same function.
Crank: The component of the bicycle that helps convert your leg motion into forward momentum by attaching to the pedals, chain and rear wheel. As you push down on the pedals, the crank turns the chainring, which pulls the chain and causes the rear wheel to roll forward.
Hub: The center of the wheel where the spokes attach. The hub has bearings inside of it, allowing it to roll. The rear wheel also holds the cassette at the hub, connecting it to the drivetrain.
Quick Release: Quick releases--consisting of an axle, nut and lever--allow you to quickly and easily remove the wheels from the bike by hand. Proper use of the quick release is essential for your safety. If you don’t know how to use one, ask your friendly professional at your local bike shop
Rim: The metal or carbon fiber hoop that attaches to the hub via spokes, forming the wheel. The rim also holds the tire and tube. Rims are either clincher (standard type where the tire is held on by the air pressure of the tube) or tubular (where the tire is held on by glue).
Frame: The heart of your bicycle. The frame consists of several tubes of steel, aluminum or carbon fiber and hold all of the components on the bicycle.
Fork: The fork attaches to the front of the bicycle frame and holds the front wheel. Mountain bike forks can be either rigid or suspended, meaning they move up and down to negate bumps in the trail. Road bike forks are generally rigid.
Butted: Metal bicycle frames of a higher quality have butted tubes. They are thicker at the ends for strength and thinner in the middle for reduced weight.
Headtube: The headtube is at the front of the frame and houses the fork and headset bearings.
Dropouts: The dropouts are where the hub axles sit to attach to the frame.
Seatpost: The seatpost connects your seat to the frame via a lightweight post. Some road bikes forgo the seatpost altogether and attach the seat via an extension of the frame.
Seatpost clamp: Secures the seatpost to the frame, preventing it from moving up or down.
Headset: The headset is housed in the headtube of the frame, and consists of bearings and cups that hold the bearings. The headset allows the fork to turn side to side, allowing you to steer the bike safely.
Stem: Just above the headset is the stem. The stem attaches to the fork on one end and the handlebars on the other. Proper installation of the stem is crucial for safety and proper performance.
Travel: Travel describes the amount of suspension motion at the wheel of a suspension bicycle. So, for example, if a full suspension bicycle is described as having 100mm (4 inches) front and rear it means both the front and rear wheels move (or travel) 4 inches. Short travel bikes are generally designed for racing or recreational riding, while long travel bikes are generally designed for more aggressive riding.
Rolling weight: Not all weight on a bicycle is created even. Because rotating mass (your tires) requires more energy to move than stationary mass (your seatpost) you will hear many bike geeks talk about “rolling weight.” Reducing the weight of rotating components, or rolling weight, is generally more advantageous than other non-rolling components on the bike.
Alloy: Alloy is a combination of metals “alloyed” or mixed together to increase the strength of the metal. In the case of the bicycle, it allows bike builders to make frames that are stronger and lighter. There are both steel and aluminum alloys used for bicycles, though you will often hear aluminum frames referred to as “alloy.”
Carbon: Carbon fiber is the current wonder material for creating high-end bicycles. Carbon fibers are woven into lightweight sheets which are impregnated with resin and then wrapped around a mold in the shape of a bicycle frame or component. This then goes into an oven where it is pressurized and heated. The pressure removes any imperfections like air bubbles and the heat activates the resin, making it very strong. Carbon frames can be half the weight of their metal counterparts.
Chamois: Pronounced “Shammy” in the United States, the chamois is a synthetic pad inside cycling shorts that pads and reduces friction to the area that comes in contact with your bicycle seat. A good pair of cycling shorts are worth investing in if you ride regularly.
Baggies: Baggies are shorts for riders who eschew the Lycra look. The best consist of an inner short with chamois and an outer short made from a lightweight synthetic material.
Jersey: While you can certainly ride in a shirt, a jersey signifies your acceptance into bike geekdom. Many jerseys are slim fitting to cut down on wind-induced flapping and have pockets in the rear to carry extra water bottles and gear. Mountain bikers are generally more inclined to wear jerseys that are looser fitting and don’t have pockets. Either type are available in technical fabrics that are adept at wicking moisture.