Head Tube Angle
Summary Axle-to-crown is a fork-length measurement taken between the center of the front axle and the crown-race seat at the base of the steerer. It helps determine the…
Velopedia Entries
An evolving encyclopedia of cycling brands, technologies, components, and history.
Axle-to-Crown
Summary Axle-to-crown is a fork-length measurement taken between the center of the front axle and the crown-race seat at the base of the steerer. It helps determine the…
Hub Motor
Summary A hub motor is an electric drive unit built into the front or rear wheel hub of an e-bike. It turns the wheel independently of the bicycle’s…
Mid-Drive Motor
Summary A mid-drive motor is an e-bike drive unit positioned near the bottom bracket that sends rider and motor power through the bicycle’s drivetrain. Because the motor can…
Effective Top Tube
Summary Effective top tube (ETT) is the horizontal distance between a specified point on the head tube and the seat-tube or seatpost centerline. It provides a consistent frame-length…
MTB Geometry
Summary MTB geometry is the collection of frame, fork, and wheel dimensions that determines how a mountain bike fits, steers, and positions the rider between its axles. Measurements…
Instant Center
Summary The instant center is the point about which a suspension member is momentarily rotating at a specific position in its travel. On a single-pivot bike, it coincides…
Front-Center
Summary Front-center describes the distance from the center of a bicycle’s bottom bracket to the front-wheel axle. It is a useful indicator of how the front wheel is…
The Rise of Full Suspension — 1990s Breakthroughs
Summary The 1990s transformed full-suspension mountain bikes from experimental machines into viable production bicycles. Improvements in rear shocks, aluminum frame construction, suspension forks, pivots, and racing development allowed…
Shimano’s Influence on MTB — From Deore XT to Di2
Summary Shimano has influenced mountain biking through purpose-built component groups, indexed shifting, trigger controls, clipless pedals, braking systems, chain-stabilizing derailleurs, and electronic drivetrains. Deore XT arrived in 1982…
Head Tube Standards
Summary Head tube standards define how a bicycle frame, headset, and fork steerer fit together. Compatibility depends on the frame’s bearing interface, upper and lower head tube diameters,…
Suspension Sag Adjustment
Summary Suspension sag is the amount a bicycle’s fork or rear shock compresses under the rider’s weight in a normal riding position. Setting sag establishes the bike’s operating…