Optimal Tire Pressure For Cycling

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updated 7.21.2020 - The following methods are still relevant today.

Determining Optimal Tire Pressure

I will updating this post as new methods become available.  If you find new methodologies, please let me know via email (VincentVergaraFitness@gmail.com), leave a comment below or 

METHOD #1:  Online Calculator

http://www.dorkypantsr.us/bike-tire-pressure-calculator.html  Like the graphics used in this post, the website looks vintage/ old school, but it still works like a champ!  Based on your body weight, the weight of your bike, tire width and estimated weight distribution (aero vs. not aero), the calculator will tell you how much to inflate the front tire and rear tire.

The calculator tends to give slightly lower numbers than what you'll get from manually calculating it. When I used the single wheel calculator, it was 2 psi lower than my calculated number. The total body weight calculator was 5 psi lower than my calculated value.

METHOD #2:  Chart

Based on your body weight and tire size, use this chart to determine your tire pressure.  Keep in mind that this won't provide suggestions for the front and rear tire.  If you choose this method, assume the recommended tire pressure applies to only the rear, and expect to drop the front pressure slightly.
Michelin Tire Pressure Chart

METHOD #3 - Frank Berto Method

The step-by-step method below was created through the experimental finding that a ~15% tire drop produced the optimal amount of tire contact for cornering.  For in depth information, I recommend reading an article called "All About Tire Inflation" by Frank Berto.
  1. Weigh yourself while carrying bike (bike + rider).
  2. Measure weight distribution.
    • Make sure bike is level- Account for the height of the weighing scale.
    • Sit on the bike in your dominant position (hoods, drops or tops)
    • Record front wheel weight
    • Record rear wheel weight
  3. Check for errors in measurements.
    • The front wheel weight and rear wheel weight should equal the weight in step one.
  4. Calculate percentage of weight distribution
    • Divide front wheel weight by total weight
    • Divide rear wheel weight by total weight
  5. Calculate difference between weight percentages.
    • Subtract big percentage by smaller percentage.  55% - 45% = 10%
  6. Use chart to determine optimal tire pressure
    1. Subtract 10% for front wheel.
    2. Add 10% for rear wheel

FINAL RESULT EXAMPLE (MY NUMBERS):
I measured my total weight (bike + rider) which was 169.4 pounds.  Based on my numbers on the drops, I held 44.6% of my weight on the front tire and 55.4% of my weight on the rear tire- a 10% difference. Based on my total weight, Frank Berto's chart says that my optimal pressure was ~89 psi.  I subtracted 10% to get the front tire pressure (~80 psi) and added 10% to get the rear tire pressure ~98 psi.

Side Note (6.22.2011): The article also claims that a 15% drop produces optimal comfort and puncture resistance, but since the tests they performed never measured these variables, I will report my experience based on real riding conditions.  I would also like to know what others think so that we can validate this claim.
Side Note Update (7.21.2020):  After several years of centuries, crit racing and commuting, I can confirm that these tire pressures really do reduce the number of punctures and maximize grip.  Though I still feel like punctures still happen too often!

Resources:

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