ADAPTRAC changes mountain bikes' tire pressure on the fly
ADAPTRAC is a frame-mounted compressed air system that allows mountain bikers to change the air pressure in their tires, as they're riding
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.
A mountain bike with the full ADAPTRAC system
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.
About the Author
An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.
All articles by Ben Coxworth
That is rather clever - but it needs to have whole bike designed around the concept, with the top tube as the reservoir and the rear suspension as the compression pump.
@Mr Stiffy - So, as the air tank is coming up to pressure, the suspension gets stiffer and stiffer. A relief valve could be installed so that once the desired max pressure is reached the suspension would then revert to its designed characteristics but until that point is reached, I would think it would be a progressively uncomfortable ride.
re; Mr Stiffy
It must be real nice to have the money to throw away a good bike because it does not have all the latest bells and whistles. for the rest of us an add on system is the best we can hope for. I do agree that a shock-absorber (Spring damper) compressor would be a nice touch.
Designing the pump to pump to a higher than maximum tank pressure and venting into the tank through a tiny hole would minimize the ride changing with tank pressure, and so would running hydraulic fluid through a motor at significantly lower pressure than the ride control valve contains.
Interesting idea for single track / trail riding - like the adjustable seat posts you can buy. But realistically too expensive / complex / not essential for the most riders. Also I'm slightly worried by the connection of the air-line to the axel - one hit with a rock / tree stump and it's gone.
The people who'd really benefit from such a system are the people too stupid to realise they need to pump their tyres up and have the pressure automatically adjusted.
...I do love the bike tech articles - keep em coming!
It would be great if they designed one of the hubs to actually be the pump to pump up the reservoir while going down hills. In this case you would never have to recharge the tank as it would be constantly topped off.
I can see this really catching on with the x-country racing crew if the device can be made light, compact and easy to use. In a race situation, tire-pressure is just about as important as tire type/tread in how one's bike performs in relation to the course conditions. The right combination of wheel set, tire and tire pressure can make or break how a bike rides. People are already easily spending $1000+ on wheel-sets alone so why not go "all out".
I bet it ads ten pounds to the bike.
1.5 pounds for the equipment .6 pounds for the liquid CO2 so 2.1 pounds minus the weight of the hubs already on the bike.
Having hard tires across firm terrain will pay for that penalty within a couple of miles.
Cool idea, i wonder how well those carbon seals keep pressure in the tire
i would love this on my motocross bikes as well, adjusting tire pressure for the terrain is very handy. Super soft in super soft beach sand and median for dirt
Perfect for fat bikes. Needs to be compatible with 170+ rear hubs though and larger volume air can likely required :-)
Interesting idea. It needs some refinement, but it could get there. Disc brakes looked ridiculous at first too.
Question - can it generate enough airflow to re-inflate a tubeless tyre after a burp (or small puncture)???
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