With all the wet weather we have had this winter, you may have started to question some of your basic assumptions about biking in the rain. As you ride through puddles and speed over pavement with standing water you might ask yourself – can a bike hydroplane like a car?
The short answer to this question is no, but the reasons why a bike does not generally hydroplane are fascinating. Hydroplaning is when a tire rides on a cushion of water resulting in a sudden and total loss of traction. This usually occurs at high speeds on pavement with standing water. This can be a dangerous condition when driving a car, but the same conditions don’t really apply to biking and bike tires. Car tires create a square road contact and have a straight leading edge with the pavement that makes it easier for a car to trap water under the tire as it rolls. Bike tires have a different relationship with the road since bike tires are designed to lean into corners. The bike tire has a rounded contact with the road which pushes the water to either side of the tire more efficiently.
The next thing that is working for the bike tire is that it is narrow and inflated to a relatively high tire pressure. Car tires are wide and inflated to a fairly low tire pressure. The wide tire and low tire pressure can make it difficult for water to escape from the middle of the car tire. Bike tires are narrow causing less water to contact the leading edge of the tire and the high tire pressure is good at pushing water out from under the tire.
The last consideration when thinking about a bike hydroplane scenario is speed. A car travels fast leaving less time for the water to be dispersed and exasperating the conditions already mentioned. Some calculations have figured that a bike would have to travel in excess of 70 mph to approach the conditions needed to hydroplane. A formula often used to figure this out is Speed (in knots) = 9 X the square root of the tire pressure (in psi), good luck with the higher math. The result is that you probably cannot go fast enough to actually bike hydroplane.
Now that you are relieved that your bike is not going to hydroplane, it is not time to relax. Riding in rain and wet weather can still be dangerous. Hidden potholes and slick surfaces can cause a sudden loss of control and crash a bike before the rider knows what has happened. Be alert when riding in wet weather; ride slower and increase the distance between cars to give you more time to react. Lastly, have the right gear and accessories so you are not distracted by the conditions and can actually enjoy the unique experience of riding in the rain.