We’ve never seen inflating bike tyres as a major hassle. Changing a flat, sure, but the simple act of adding pressure? Nevertheless, it’s a problem that the guys at PumpTire reckon they’ve found a solution to, with what they claim to be the world’s first self-pressurising bicycle tyre.
The basic premise is that the rolling motion of the tyre draws in air via a clever internal mechanism and this air is then used to inflate the tyre to a preset pressure. It’s then automatically kept at that pressure, compensating for any air lost through the sidewalls over time.
Each PumpTire set consists of a special tyre, inner tube and detachable valve. Unlike a conventional tube, this one clips into the tyre and air is able to pass between the two. The valve screws onto the valve stem of the tube and allows air from outside the tyre to move into a lumen, or hollow tube, around the circumference of the tyre. As the tyre rolls, air is pushed from the lumen into the inner tube – think of squeezing a tube of toothpaste. Once the desired pressure is reached, the valve automatically shuts off.
Two tyres are in development. The City Cruiser (26 x 1.5in) is designed for commuters or urban cyclists and self-inflates from flat up to 65psi. The City Pro High Performance tyre (700c x 28mm) allows you to set your own pressure between 65 and 95psi by altering a setting on the valve. The valve is compatible with Schrader or Presta adapters, so you can pump the normal way if you want.
As the technology is still at the prototype stage, PumpTire, in true Dragon’s Den fashion, are looking for backers to bring their design to reality. They need help to complete engineering work and testing, and purchase materials. Rather than buying a share of the company, investors are being promised tyres in return – $45-74 will get you everything you need to run one City Cruiser tyre.
The company are looking to reach a target of $250,000 within 41 days. At time of writing they’re on $2,053 so they’ve got a long way to go yet. Is this a project that needs backing? Is it practical in the real world? And what happens when you puncture? Head over to their website and make your own minds up.