3 lbs seems a small amount to me for the application,
Boyle's Law: when the volume of a closed container is cut in half, the pressure of the gas inside doubles
On a fork with 8" of air column ,and no precharge, the air inside the fork is at atmospheric pressure (14.7psi absolute) when the fork is fully extended. If the fork has 8" of air at the top, the air pressure would be 29.4psi at half way through its travel (4"). At 6" of compression (3/4 of the way compressed), the pressure would be 58.8psi absolute). Acting on a 40mm fork end (about 2 1/2 square inches), the force would be 147 pounds minus the 2 1/2 sq in x 14.7 psi atmospheric pressure acting in the opposite direction (35.75) or 111 pounds PER FORK! The air in the two forks would be exerting 222 lbs of force trying to resist compression at 3/4 travel.
Now add 3 psi preload to the calculations. 17.7psi at full extension. 35.4 psi at 4". 70.8 psi at 6". Times 2 1/2 sq in. = 177 lbs. minus 35.75lbs = 141.25 lbs x2 = 282.5 lbs vs 222 lbs with no precharge.
60 lbs of force difference to the front of the bike from ONLY 3psi!!!!
I am also surprised that they make a gage that is that intricate that will properly show just 3 degrees
First, I know you meant to say precise instead of intricate and psi instead of degrees.
Precise low pressure tire gauges are EXTREMELY important for many forms of racing. A typical Top Fuel dragster will run about 6psi rear tire pressure. Swamp buggies, sand rails, and monster trucks all run very low tire pressure.
There are also innumerable industrial needs for low pressure air gauges.
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