An Endo, short for “end-over-end,” is a cycling crash or incident where the rear wheel lifts off the ground, causing the bike and rider to pivot forward over the front axle. In its most extreme form, the momentum carries the rider completely over the handlebars, a high-stakes event often triggered by sudden front-wheel deceleration. This can occur due to panic-braking, a mechanical failure where the front wheel “locks up,” or striking an unexpected obstacle like a deep pothole or a hidden root on a technical trail in a mountain bike or gravel race. For a cyclist, an endo is a visceral reminder of the physics of weight distribution.
While “performing an endo” is sometimes done intentionally in trials riding or mountain biking as a display of technical control (often called a “stoppie”), a race-day endo is almost always an accidental loss of stability. The resulting impact often leads to characteristic “over-the-bars” injuries, specifically to the wrists, collarbones (clavicles), and shoulders, as the athlete instinctively reaches out to break their fall. Preventing this forward pitch requires a mastery of braking modulation—balancing the power between the front and rear brakes—and shifting the center of mass rearward (“getting behind the saddle”) when descending or navigating hazardous terrain.
Understanding the mechanics of an endo is essential for safety during high-speed descents or in the tight quarters of a Peloton. It underscores the necessity of constant environmental scanning and the development of “soft hands” on the controls to avoid abrupt, jerky break inputs.
