ADAPTRAC changes mountain bikes' tire pressure on the fly
By Ben Coxworth
April 17, 2012
Like a lot of other factors involved in mountain biking, setting the air pressure of the tires is a matter of compromise. Keep them too soft, and you can’t go as fast as you’d like on smooth stretches of the trail – keep them too hard, and they’ll just bounce off of roots and rocks instead of gripping them. As it stands, most bikers go for a “Jack of all trades, master of none” setting, that allows for some traction and some speed. The folks at ADAPTRAC, however, apparently think that such a compromise shouldn’t have to be made. Their new system allows riders to inflate or deflate their tires as conditions dictate, while they’re riding.
The ADAPTRAC system works as follows ...
Toggle switches on a handlebar-mounted control unit allow riders to add or remove air from their front or rear tires. That unit can also be mounted on the stem or down tube.
If more air is requested, it is released from a down tube-mounted rechargeable compressed air tank – these tanks are available in a variety of sizes. An attached regulator brings the pressure of the stored air down to a system-friendly 175 psi, as it leaves the tank.
That air travels through one of two frame-mounted hoses, to either the front or rear ADAPTRAC wheel hub. The hose/hub couplings incorporate “special, extremely low friction rotary seals,” to keep air from leaking out while allowing the wheel to spin freely. From the hub, the air goes through another hose, that leads out to the tire’s valve stem.
When softer tires are needed, presumably air is just released from them into the atmosphere. The current air pressure of the tires is displayed on two bar-mounted analogue gauges.
ADAPTRAC's Paul Skilbeck tells us that the product is still in the late prototype stage, and that a price will be announced shortly after the system is presented this week at the Sea Otter Classic Expo in Monterey, California. He added that the total system weight is about 690 grams (1.5 lbs) with an empty 9-ounce (266 ml) CO2 tank – keep in mind that the custom hubs would replace those presently on the bike.