Biking in a thunderstorm is highly unsafe and should be avoided due to severe electrical and environmental hazards. A cyclist caught out unexpectedly needs to understand the specific dangers to take immediate, appropriate action. This guide explains why remaining on a bicycle during a storm presents a significant threat and provides actionable steps for seeking safety.
The Primary Danger: Lightning and Electrical Risk
A cyclist’s position often makes them the tallest object in an open landscape, increasing the likelihood of a direct lightning strike. Lightning seeks the shortest path between the storm cloud and the ground, and a person sitting upright on a bicycle can inadvertently become that elevated target. The sheer power of a lightning bolt, which can carry over 100 million volts, makes any exposed position extremely dangerous.
The common belief that rubber tires offer protection from lightning is a misconception. While rubber is an insulator, the thin tire material is insignificant against the enormous voltage of a lightning discharge. Furthermore, the metal frame and handlebars of a bicycle are highly conductive, meaning if a strike occurs, the electrical current will pass directly through the metal and the rider’s body to reach the ground.
A lightning strike does not need to hit the cyclist directly to cause harm; a strike nearby can be dangerous through ground current or step voltage. When lightning strikes the earth, the massive electrical charge spreads outward across the ground surface. This creates a voltage gradient, meaning the electrical potential is different at various points along the ground.
If a cyclist has their feet apart, the difference in voltage creates a step potential, which can drive a current up one leg, through the body, and down the other leg. This ground current is responsible for many lightning-related injuries and fatalities, even when the strike point is several yards away. Getting off the bike is necessary to minimize this specific electrical risk.
Secondary Hazards of Storm Riding
Beyond the immediate threat of electrical discharge, thunderstorms introduce environmental factors that compromise a cyclist’s control and visibility. Heavy rain dramatically reduces visibility for both the cyclist and surrounding traffic, making it difficult to spot road hazards. Low light conditions combined with a downpour make a cyclist less discernible to drivers, increasing the risk of collision.
Water accumulation on roads creates slick conditions that severely affect tire traction and braking capability. Oil and grease residue on the asphalt mixes with the first rain, creating a particularly slippery surface. Braking distances increase significantly on wet roads, and smooth metal surfaces like manhole covers and bridge grates become extremely slick and dangerous to cross.
Strong crosswinds can destabilize a cyclist, leading to a sudden loss of balance or being pushed into traffic. These powerful gusts can also turn small debris into dangerous projectiles. The storm may scatter fallen branches, loose signs, or other large objects across the road, which can lead to crashes if obscured by heavy rain or standing water.
Seeking Immediate Shelter and Safety
The moment you hear thunder, you are within striking distance of lightning, which can occur up to ten miles from the storm’s center. Use the 30/30 Rule: if the time between seeing a lightning flash and hearing the thunder is 30 seconds or less, seek shelter immediately. Once safely sheltered, wait 30 minutes after the last clap of thunder before resuming your ride, as electrical activity can linger.
The safest place to wait out a thunderstorm is inside a substantial, fully enclosed building with wiring and plumbing. If a building is unavailable, a hard-topped vehicle with the windows rolled up offers a protective enclosure, as the metal shell can direct current around the occupants in the event of a strike. Avoid seeking shelter in open structures like sheds, picnic pavilions, or under isolated tall trees, as these offer no protection and can increase the strike risk.
If caught in an open area with no safe structure nearby, dismount your bicycle immediately and move away from it, as the metal frame acts as a conductor. Move to the lowest possible ground, such as a ditch or valley, while avoiding any area that could quickly flood. Crouch down low to the ground with your feet and knees together, touching only the balls of your feet. This position minimizes your height and reduces the risk of step potential by limiting the contact area between your body and the ground.