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PumpTires: Bike tires self-inflate as you ride

A startup called PumpTire is trying to bring its prototype high-tech urban bike tires to market. They automatically inflate as you ride.

The specially designed valve (left) draws in air as the bike's wheel spins. The air is channeled into the "lumen" (right), which collapses as the tire rolls across the ground, squeezing the air into the inner tube. PumpTire

Anyone who rides a bike would agree that flat or low-pressure tires are a drag. But why fiddle with a pump when the tire can inflate itself?

San Francisco-based startup PumpTire has invented just such a self-inflating tire. Aimed at urban cyclists, the tire includes a built-in pumping mechanism that uses the spinning motion of the wheel to gather air and the weight of the bike to push the air into the inner tube.

"Some people do not inflate their tires often enough, which can lead to accidents or flats," said Benjamin Krempel, founder of PumpTire. "With PumpTire automatically inflating your tire, you are increasing the safety and performance of your bike whenever you ride."

Krempel and team have patented their technology and are raising money on Kickstarter in hopes of commercializing two types of tires, the City Cruiser and City Pro (one's for the casual rider, the other for the urban commuter). The tires use a technology called a peristaltic pump. Krempel's inspiration came from his experience in the medical-devices industry; the pumps are used in medical applications such as IV fluid drips and heart-lung machines, he said.

The PumpTire features a special valve which, like a conventional valve, can attach to a bicycle pump for manual inflation but also takes in air as the tire spins. The air is channeled into a small tube, or "lumen," that runs around the outside of the tire, where it makes contact with the ground. The weight of the bike squeezes the air out of the lumen and into the inner tube. The specially designed valve automatically shuts off and stops its air intake when the desired tire pressure is reached.

The PumpTire team needs to raise $250,000 to get additional funding. If they hit that goal, we'll be watching to see if their tires catch wind.