How to Air a Tire

All about Tire Inflation
The easiest, and probably the most neglected maintenance task that bicycle owners can perform on their own, is correct tire inflation. Sadly, inadequate tire inflation also contributes to more trips to the shop for repairs and lots more work to ride on the part of the cyclist.

Why Do My Tires Go Flat On My Bike But Not My Car?
The tires on your car hold a lot more air volume under a lot less pressure. They are also significantly thicker and heavier than bicycle tires because hitting a pothole at 65 mph in a big heavy car full of people is more potentially damaging to the car tire, then damaging to your bike tire hitting the same pothole at 10 mph. If you had tires proportionally as heavy on your car, as on your bike, your bike would weigh a lot more than it needed to weigh and not corner in a supple manner!

Interestingly enough, many car accidents and tire failure in automobiles are caused by improper inflation, so check your car pressure too after reading this!

Anyway, because your tires and tubes on your bike are thin, and the air inside them is under a great deal of pressure and the voids between the molecules in the rubber are larger than the air molecules, air naturally escapes. If you don't ride your bike for a week, you can loose 5 pounds or more, just letting your bike sit around. Road bikes with skinny tires that hold 95 to 125 (even more!) pounds per square inch of air, loose even more air and need to be checked for every ride, even if you ride every day. Matter of fact, if you go on a long ride, those air molecules heat up due to the friction of the tire on the ground and the brake pads on the rim - and you loose even more air because hot air molecules move around a lot and escape out of the voids in the rubber molecules at an even greater rate.

So my pressure is low, why is this bad?
Well, besides the fact that you work harder pedaling the bike because more of the tire surface contacts the road increasing friction and slowing you down, under inflation can damage the tire and rim. First of all, the tire is designed to protect the rim by absorbing impact in the form of bumps in the road. On a mountain bike, that bump may be a boulder or log, on a road bike that bump may be a pothole, a stick, some metal - what have you. If the tire isn't protecting the rim from impact your wheels in the best case scenario, just get knocked a little out of true from perfectly round. In the worse case scenario the rim gets a flat spot or a bend in the wall of the rim and/or and braking surface that compromises the structural integrity of the wheel and makes it unsafe.

Also, that same pothole, which doesn't damage your rim, deforms the tire when you ride in it. If the tire deforms too much, the sidewall can be damaged more easily, potentially causing a major blow out and a tire that is ruined before you wear it out. The tube can also get pinched between the overly flexible tire and the rim, which causes a pinch flat.

OK, How Do I Inflate A Bike Tire?
Two things to know first. One: What kind of valve do you have on your tire? Two: How much air should go into your tire?

Presta valves, like the skinny valve on the left, generally hold more pressure than schrader valves, which like the one on the right, which are like the valves on a car. Since the valve diameter itself is thinner, the rim itself can be skinny without compromising strength, which a bigger hole might do.

As you can see the knobby mountain bike tire on the left, is designed for a range of air pressures. If you were to ride this mountain bike tire in the dirt at 65 psi (psi is the abbreviation for pounds per square inch) you wouldn't have a whole lot of traction. If you weighed rather a lot and rode this bike on the lower end of the inflation range over rocks and sticks, you could get a pinch flat. With mountain bikes, off road, tire pressure has an awful lot of effect on traction.

As you can see on the road bike on your right, there is an upper limit of quite a bit more than the mountain bike. Traction is important on road bikes too, as well as comfort (highly inflated tires have very little "give," or the ability to absorb road vibration), but look how skinny the tire is - it does not protect the rim at all. Proper inflation is critical here for ride quality as well as protecting the tire and rim from damage from road hazards.

So now you need a pump

Floor pump on the left, center photo of frame pump, and CO2 pump (with cartridges) on the right.

The floor pump is used for maintaining tire pressure at home BEFORE you ride. Good floor pumps have a gauge built in, so you don't have to take the pump head on and off to check your pressure. The frame pump and CO2 dispenser are used when you have a flat on the road or trail and you are ready to inflate your newly replaced tube in the tire.

The rule is - check before each ride

So now you want to know how to get the air in the tire? Well look here

The tire should be rotated valve down as not to apply stress to the pump hose. As you can see, the valve locks on by folding the lever up. Yes, that's counter intuitive, but that's how it works. The floor pump (if you got it from us) will either have a double head with a skinny hole and a fatter hole for each valve type OR a smart head. Ask if you aren't sure, or if you didn't get the pump from us. We may ask you to bring the pump by, if we aren't sure from your description.

With the schrader style valve, all you have to do to get air in the tire is take off the plastic valve cover, attach the pump and pump. That first pump stroke on the pump will pressure the pump hose on the floor pump and give you a correct reading on the pump gauge.

Presta style is more complex. One has to remove the plastic valve cap and loosen the brass top - carefully. You don't need to really twist hard.

The presta valve on the left is closed; the picture on the right shows it open (both with valve cap removed).

Give the valve a tap to let a tiny bit of air out and break the seal inside the valve, and use the floor pump exactly as above.

Hand pumps and CO2 work a little differently. Let us explain how they work, as not all pumps are created the same. If you are buying a mobile air supply like CO2 or a hand pump, we are happy to demonstrate the correct use for you.

That's it!
You should be ready to go, once you've filled your tires to the recommended pressure.