Pressurized bike frame fills flat tires
When it comes to portable bicycle tire-inflating devices, hand pumps require a lot of effort, while CO2 cartridges are single-use only. The aluminum Choka bike frame offers an alternative, by doubling as a compressed air tank.
Designed in the French Pyrenees region, the Choka features an airtight down tube with a Schrader valve at the bottom. While still at home, the user attaches the hose of their floor pump to that valve, then pumps the down-tube chamber up to 175 PSI (12 bar). A "security valve" on the underside of the tube automatically lets excess air out if it gets overinflated.
On a subsequent ride, should a tire need inflating, the rider runs an included air hose from the frame's air valve to the air valve on the tire. Utilizing a dial on the frame-end of the hose, they can then control the rate at which the air is released.
This means that they can gradually transfer a bit of air to top up a soft tire, or they can deliver a big rush of air to seat and inflate a tubeless mountain bike tire.
According to the designers, one "frame-full" of air should be sufficient to inflate three 27.5 x 2.80 tires to 22 PSI (1.5 bar) or two 700 x 45C tires to 60 PSI (4.1 bar).
Plans call for the Choka to be available in two models – the AGHATA (AGgressive HArd TAil) enduro/all-mountain frame, and the Gravaël Raw gravel frame. The former is compatible with 29- or 27.5-inch wheels, or a combination of both, while the latter can be set up with 650B or 700C wheels.
Should you be interested, the Choka is currently the subject of a Kickstarter campaign. Assuming it reaches production, a pledge of €990 (about US$1,163) will get you either an AGHATA or a Gravaël Raw frame, including the air system, bottom bracket and headset.
And if you like the idea of adding a home-pumped reusable compressed air chamber to your existing bike, you might want to check out the frame-mounted RideAir.
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But with the air in the frame at pressure, might it not be possible that a crash sufficient to bend the frame might result in a small explosion with metal shrapnel being blasted upwards? Hmmm Be hard to ride with your legs crossed.
@joeblacke, we like the idea! For a suspension system that woudl also increase grip we should definitly go for full suspension frame. No risk of "explosions" of any kind:
1 there is a security valve just to relief stress on the welds if the bike is in a non pressurized airplane.
2 the pressure / volume ratio is very very small, if the frame would brake an air leak similar to the ones you have when having a flat would happen.