The main reason I went for the Legend Air Ride suspension over the standard rear suspension(s) that came on the ultra (reused for the Lehman trike conversion) was the softer ride.
I weigh 140 lbs and my wife about the same. The stock rear suspensions were just too stiff (no matter the amount of air pressure) to provide a smooth ride for either one-up or two-up riding.
The standard HD suspension(s) use springs with air pressure assist. If the spring rate is too great for the load then you get a stiff ride. The Legend Air
ride suspension doesn't contain springs, but instead a Kevlar air-bladder to support the weight at the rear of the trike. Regulating the air pressure in the
bladders will change both the ride height and stiffness of the suspension.
The Legend suspension kit comes with a 12V air pump (that mounts under the
battery) that is controlled by a handle bar mounted push-button switch. Depressing one button allows you to increase air pressure, while pressing the other button allows you to decrease air pressure.
I simply load the trike with people and cargo, increase the air pressure until the suspensions are extended fully (ride height at maximum) then slowly decrease the air pressure until the ride height drops slighty. This procedure seems to produce the best ride with the particular load that you are carrying.
I also adjust the rear tire pressure according to the load so that I have some deflection in the sidewall of the radial tires. I typically run 18 - 20 psi in the rear tires without the tires overheating (here in the high Arizona heat).
Hepengr