Momentum USA Nov/Dec 2011
FOLLOW THESE INFLATION TIPS FOR A SMOOTHER AND MORE EFFICIENT ROLL how to PUMP UP YOUR TIRES WRITER ANNE MATHEWS ILLUSTRATOR BROOKE APPLER HOW MUCH AIR Pumping tires to their optimal pressure is pretty straightforward but it helps to have a little knowledge about how tires and inner tubes work Your bikes tire is kept infl ated by a rubber inner tube situated snugly inside the tire nestled in the rim The inner tube valve protrudes from the rim at right angles to the rim surface through a drilled hole set between two spoke holes If overinfl ated your tire may lose traction blow off the rim or burst And an underinfl ated tire is more vulnerable to pinch fl ats called snake bites due to the two distinctive holes that it produces in an inner tube Without enough air a Schrader valve tube can also slide around inside the tire until the valve stem moves to the side and eventually tears at the valve stem base a hole thats diffi cult if not impossible to patch To see if youve gotten the pressure right sit on your bike and check the tires At optimal infl ation they should bulge out just a teeny tiny bit where they make contact with the ground No bulge means theyre probably overinfl ated too much bulge means you can put more air in there TIP Align your inner tube valve with the tire pressure information on your tire That way youll have the maximum and minimum tire pressure in plain view the next time you go to infl ate your tire bells whistles bike curious TYPES OF PUMP P roperly in ating a tire is a magical thing its a simple adjustment that can result in a major improvement in your ride Underin ated tires have excess surface area in contact with the ground creating more friction to work against theyre also prone to ats You can sit on a bike and see underin ation at work Are your tires splayed out where they meet the ground Can you squeeze either tire between your ngers with ease If youre working really hard to get moving and your bikes in otherwise sound shape chances are that your tires need air STEP ONE Look It Over To determine how much air to put in your tire read the PSI pounds per square inch recommendation printed on the sidewall ese numbers are based on manufacturer calculations balancing safety and performance Its best to in ate to at least the minimum recommended PSI but try not to go too much over the max even though you sometimes you can Di erent tires have di erent specs a good rule of thumb is that your tires should be rm but not rock hard Now check the tire to make sure its correctly seated on the rim Make sure that the valve sticks out at right angles to the rim and that theres no dry rot cracking on the tire sidewalls or excessive wear on the tire surface STEP TWO Pump It Up Remove the plastic dust cap from the valve and place it somewhere close by as these are easily lost If you have a Presta valve loosen the knurled nut completely and Floor pumps large solid sturdy upright standing pumps with a built in pressure gauge and mini pumps small and portable usually come with Schrader and Presta valve settings The third variety the gas station pump fi ts only Schrader valves Use caution when infl ating at a gas station those powerful air compressors can quickly cause dangerous blowouts Make sure the tire is properly seated on the rim then proceed incrementally using a pressure gauge to check your progress Schrader Valve Presta Valve tap the needle gently inward to make sure its not stuck in place if the tire already has air inside some will hiss out when you do this Make sure the tting for your pump is correct for your valve the wider aperture is for Schrader the narrower one is for Presta If theres a locking lever at the pump head make sure its unlocked Slide the pump head onto the valve Once the pump is rmly attached secure the locking lever to x the head in place Start pumping checking the pressure as you go until Pressure Gauge Valve Adapter you reach the recommended PSI Unlock the lever and quickly remove the pump head If you have a Presta valve re tighten the knurled nut Replace the dust cap and youre done Anne Mathews lives in Seattle where she rides bikes fi xes bikes and plays music with the Toy Boats thetoyboats com the Lonely Coast thelonelycoast com and Orkestar Zirkonium orkestarzirkonium com The late Sheldon Browns website has a great in depth rundown of the physics of tire infl ation sheldonbrown com tires html WHATS YOUR VALVE Schrader vs Presta Inner tube valves in North America mainly come in two varieties Schrader or Presta Schrader valves are fatter with a spring loaded pin and a plastic dust cap Theyre common on less expensive bikes older bikes mountain bikes and utility bikes Theyre also found on car tires Presta valves are narrower and springless with a knurled nut on the valve needle that acts as a built in valve cap Appearing mainly on highperformance bikes Presta valves hold higher air pressure than Schraders and often include a useful lock nut at the valve base to hold the valve steady at the wheel rim Each valve type requires its own pump fi tting but most bike pumps come with a dual or reversible fi tting that adjusts to fi t either valve Only Schrader valve inner tubes can be pumped up with gas station pumps but you can buy an inexpensive screwon brass adapter for Presta tubes that allows you to use Schraderfi tted pumps NOV DEC 11 MOMENTUMPLANET COM 18
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