The expensive part of a good air shock is “multiple shocks” built into the system… were the low end shocks have none or maybe one.
On a car you can get away with it, because the weight is directly over the shock. Another words the weight is one to one or a 1:1 ratio. If say… the back end of a car weighs 1500 pounds each shock is taking 750 each pounds of force.
On a bike this is not the case. Especially on a soft tail. The ratio of “weight to shock” is more than 2: 1 as much as 3:1 depending on position it’s in. This means that the bounce in the air shock is amplified by that ratio. For every inch of bounce at the shock, you will get 2 inches to 3 inches of bounce at the axle. You will feel 2 inches to 3 inches of bounce.
I’m I making any sense here?
Look at the distance from the pivot of the swing arm to the end of the shock. Then look at the distance from the pivot of the swing arm to the axle. This is the ratio I’m talking about.
The long / short of it, your not going to like the lack of control of a low end shock as apposed to a high end shock set.