Tuesday, July 12, 2016

Tire Air Pressure Settings For The 21st Century

 Recently new research by several independent sources has shown that, in all likelihood, your ideas about what is "right" for air pressure is wrong in terms of your bicycle. There is also a long history of repair related to poor air pressure maintenance that could easily be rectified by doing a couple of simple things. The long and short of it is this: Your tire air pressure is probably too high or too low.

Too High: There has been a lot of research recently that points to how tire air pressures for road cyclists is affecting the rolling resistance and ride quality of their bicycles. Traditionally, the recreational cyclist has assumed that a higher pressure, or shall we say highest pressure allowable, is going to yield the lowest rolling resistance and thus, the fastest, less energy sapping ride. This has been proven to be far from the truth in reality.

Research recently published on the Silca site suggests that what we assumed about bicycle tire air pressure is all wrong. Read it starting HERE. There are about ten entries in all, and it is pretty technical, thick reading, so this may not be for everybody, but if you demand "science" then this is for you.

The short version is that while there is no "right" air pressure, there are wrong choices, and it would appear that by going to the highest allowable air pressure settings riders are actually increasing rolling resistance, work load, and lowering speeds by a dramatic amount. Conversely, low air pressures, (those just below what many would consider rideable), seem to have a less deleterious effect than previously thought, and in many cases actually will increase not only speed, but comfort levels while simultaneously reducing work load. There is much more to it than this, but there are the main talking points so far.

Too Low: On the other end of the scale we are seeing a lot of riders that do not understand tire air pressure maintenance. They typically are running far too low on air pressure and usually end up causing themselves pinch flats as a result. In the Europa repair area, we see more failures due to pinch flats than we do punctures from foreign objects. Far more pinch flats and they are almost always caused by folks that do not maintain air pressure settings on a regular basis, or know that they even need to do this.

Tubes, found in most bicycles today despite all you hear about tubeless tires, are bladders that reside inside the casing of your tire and are typically made from butyl rubber. These tubes used to be pretty thick walled back 50 years ago, and required little air pressure maintenance. This was because the thicker tube was more resistant to the passage of air molecules through its walls. The downside was that these tubes were heavy. Really heavy!

Today tubes are much lighter, and the wall thicknesses of inner tubes are really thin these days. This allows for an easier escape for air molecules. This results in as much as a 10% decrease in tire pressure in a 24 hour period on a high pressure road tire. Hybrid bike tires lose pressure at a slower rate, but they still will end up flat after several months of no air pressure maintenance. We recommend the following:
  • Road tires from 23mm-30mm (typically run from 90psi to 110 psi) Check pressure before every ride!
  • Hybrid/Gravel Road/Dual Sport tires from 30mm-45mm (typically from 30psi to 80psi) Check pressure every other ride and at least once a week.
  • Mountain Bike from 2" to 3" wide (typically from 15psi to 30psi) Check once a week minimum.
  • Fat Bike from 3" to 5" tires (typically run from zero to 20psi) Check once a week minimum. 
  • It is best to check any bicycle tire before every ride for proper air pressure!
This may seem like nit-picking, but tire pressure is one of the single most effective ways to tune your bicycle to operate at its highest potential. This gives you the power to be in control of how easy, fun, and safe your bicycle can be, Neglect air pressure maintenance and proper use and you will be working harder, have less comfort, and suffer more failures than you need to.

The choice is yours.

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