PumpTire has revealed that it has a working prototype of a self-inflating inner tube that will use a minute pump to take mechanical energy and convert it into air for the chamber.
The system is adaptable for any tube size, with the valve the significant component, something which the designer says will fit any rim and will not require special tools to install. Furthermore, the creator says you can still choose the pressure on which you'd like to run. The pump cuts out once the desired pressure is achieved.
"Exactly 100% of pneumatic bike tires suffer from pressure loss. The PumpTire system solves this problem without compromising ride quality or requiring modifications to your bicycle.” says Benjamin Krempel, the technology's creator.
"We are announcing that we've brought the design far enough along to have a working prototype! The posted photo below is a sample of the prototype and our not-yet-completed adjustable valve. The valve is designed, patented, but not yet a production piece."
The first PumpTire products will target the urban commuter and eBike markets.
Krempel adds: "Our market research shows us that the two biggest dislikes of urban commuters are re-filling their tires and replacing flat tires. By solving these two problems we can further encourage bike usage."
UPDATED: We followed up with Krempel on a few details on his design and he had this to say:
How do you maintain and set the desired pressure?
The set pressure is adjustable through the valve stem; You can see the knurled feature on the valve stem. When the tire pressure is less than the set pressure, the control system allows air to enter from the atmosphere. Once the tire reaches the desired pressure the control system closes the inlet to the atmosphere.
In the event of a puncture, how is that pressure still retained – will the tube self seal?
The inner tube is puncture resistant in the same sense that a Schwalbe Marathon tire is puncture resistant. The materials we use are different, but offer significant puncture resistance. Because of the design of the system, even if the pumping mechanism were punctured, the inner tube would not be punctured. It’s even possible that the pumping mechanism could get punctured, but the inner tube would still pump because the puncture hole is only a small hole along the length of the pump. There is no self seal in the design.
Do you have a rough cost estimate for when the tube launches?
The inner tube will be in the $30-50 range. It’s not yet fixed, however. We also plan to have basic and performance version, which would occupy different price points.
Do you have any graphics to show how it works?
We’ll come out in the next months with the design and how it works. It’s a little bit too early show the details.
The firm will debut the product on kickstarter in 2016.