Road Bike Anatomy

Frame and Fork

Frame

A road bike frame defines the riding characteristics of a complete road bike. Bike fit and geometry is determined by the frame and how the various tubes are connected. A contemporary frame is comprised of a molded carbon fiber composite material featuring specific material layup configurations to balance stiffness and compliance, or flex.

Fork

A road bike fork is used to secure the front wheel and brake and features specific carbon composite layups to the complement the frame and its desired riding characteristics.

Headset

A headset is composed of sealed cartridge bearings, which serve as a connection point for the fork and frame. These sealed bearings can either be pressed into or dropped into/integrated into the head tube of a frame. The bearings allow the fork to rotate smoothly for steering

Cockpit

Handlebars

Road bike handlebars feature a curved drop shape to put riders in a low position for descending or sprinting and to provide more leverage on the brake levers for added control. Contemporary drop bars are compact, meaning the drop is higher and feature a flat section near the center for more comfortable ergonomics. Road bike bars come in carbon and aluminum options.

Bar Tape

Road bike bar tape is a wrap used on the handlebars to provide grip and reduce shock and vibrations which can cause fatigue and pain. Bar tape comes in a variety of materials including cork, polymer, silicone, and more. Some tape is offered with a gel backing in order to better mitigate impact.

Hoods

Hoods are the forward-pointing hand controls, mounted to the handlebars, that provide an ergonomic platform for your hands while riding. The hoods also house the hand controls for braking and shifting. These controls are in the form of paddles that can be pulled rearward for braking and pushed laterally to adjust gears.

Stem

The stem connects the handlebar with the frame and fork. Steering input from the bars is directed through the stem to the fork. Stems come in aluminum or carbon and a variety of lengths to accommodate a proper bike fit.

Saddle and Seatpost

Saddle

A road bike saddle or seat is a critical touch point that provides support for your sit bones and pelvis while riding. Both men’s- and women’s-specific saddle designs feature a variety of foam and other materials to save weight and provide comfort. Saddles are mounted horizontally but can be tilted or moved forward or back depending on rider preference.

Seatpost

A seatpost connects your saddle to the frame. Made from carbon or aluminum, seatposts come in a range of lengths and widths to match the frame design. The seatpost, held in place by the seatpost clamp, is height adjustable to accommodate the fit of the rider.

Drivetrain

Cranks

The cranks are the connection points from the pedals to the drivetrain. As you pedal forward, the cranks engage the drivetrain and move the bike forward. The cranks are connected on either side of a frame via a spindle that interfaces with the bottom bracket. Cranks are made of carbon or aluminum and come in a range of sizes that are depending on the size of bike or rider preference.

Bottom Bracket

The bottom bracket is similar to the headset, and features sealed bearings that are threaded or pressed into the bottom of the frame. The spindle from the crank arms slides into the bottom bracket, allowing the cranks to rotate smoothly.

Chainrings

A chainring is a narrow, circular ring that features sharp, evenly-spaced teeth. The chainring serves as the bicycle’s drive mechanism. It is fixed to the crank set, and the chain runs along its teeth, allowing the bike to move forward as the rider pedals.

Chain

A chain is a continuous loop of metal links, and a key part of a bicycle’s drivetrain system. By connecting the chainring to the cassette, the chain rotates the rear wheel as the rider pedals. The width of each chain varies, and is specific to the amount of gears on the bike’s cassette. Like all drivetrain components, chains only function properly with compatible drivetrain kits.

Derailleurs

Front

The front derailleur is a cable- or electronically-actuated mechanism that moves the chain to the larger or smaller chainrings. The movement is determined by the rider and their input on the shift lever at the hoods. The front derailleur is mounted to the frame above the bottom bracket.

Rear

The rear derailleur functions like the front but moves the chain across the rear cassette. It is mounted below and behind the rear axle and features a cage with pulley wheels that maintains tension on the chain as it moves between smaller and larger cogs.

Cassette

The cassette is the cone-shaped stack of chain rings or cogs which is fixed to a bicycle’s freehub body. Each ring features a different number of teeth, allowing riders to change how much distance they get out of each pedal. The larger (low) rings make it easier for a rider to climb, and the smaller (high) rings come in handy when a rider is descending or moving at a high rate of speed. Cassettes are available in a variety of gear ranges and are matched to the intended purpose of the bike, like endurance, sprinting, or cyclocross.

Wheels

Hubs

The hub allows the wheel to spin, and is fixed to the frame and fork via dropouts, or mount points, via the axle, a rod positioned at the center of the hub. Riding on the axle is a set of bearings, which give the wheel freedom of movement. Finally, a flanged cylindrical shell forms the exterior. Front hubs spin freely in either direction, and their movement is only controlled by momentum or the bike’s brakes. Rear hubs, however, feature a drive mechanism which rotates the hub when force is applied to the pedals.

Spokes

Spokes are long cylindrical, usually metal, pieces which connect the rims at the perimeter of the wheel to the hubs at the center. They often have a hook shape on one end, which secures them to the eyelets of the hub, and threaded on the other end, allowing them to be fixed to the rim with small nuts called nipples. Other types of spokes are bladed or feature a flattened shape to reduce aerodynamic drag.

Rims

Rims are the circular hoop-shaped components which form the outermost layer of the wheel. Typically made of aluminum or carbon fiber, the rim must be stiff yet very lightweight, to not compromise the rim’s shape or the bike’s efficiency. They have eyelets drilled through them, allowing the nipples to thread securely to the spokes. The walls of the rim feature subtle ridges, which serve as a place for the bead of the tire to form an airtight seal. Road bike rims will often feature a machined braking surface if the bicycle does not employ disc brakes.

Tires

Tires are the inflatable rubber casings which the bike actually rolls on. They feature tread patterns with varying compounds and designs, allowing riders to find suitable grip in a variety of terrain and weather conditions. Tires are either inflated via inner tubes or a tubeless system, which typically consists of rim tape and a liquid sealant that helps prevent air from escaping.

Brakes

Rim

Rim brakes feature two pads that engage either side of the rim via articulating arms. The pads are cable-actuated from the brake levers on the hoods. Rim brakes are mounted to the rear of the frame behind the seatpost or above the bottom bracket, as well as on the front of the fork, above the wheel. Different aerodynamic options will have the brakes integrated into the structure of the frame or fork to reduce drag.

Disc

Road bike disc brakes function like a mountain bike disc brake. Cable- or hydraulically-actuated pads pinch a rotor mounted to the hub. The caliper houses the pads and uses a cable and housing or fluid hose connection to the hoods to receive rider input. Hydraulic disc brakes on road bikes offer more power, better modulation, and greater control than rim brakes.

Pedals

Pedals connect the bottom of a rider’s shoes to the drivetrain. They consist of a clip and threaded spindle which attaches to the crank arms. Clipless pedals feature a locking mechanism that attaches to compatible shoes, giving riders more efficient power transfer. Because pedals are not universal, and vary by rider preference, they are often sold separately from complete bikes.