Your saddle should carry about 75 percent of your weight; the rest is supported by the bars and pedals. If your saddle is improperly positioned, it will carry too much weight.
Types of Saddles
Different saddles offer different padding amounts. For example, racing saddles have much less than commuting saddles. But a properly positioned, lightly padded saddle is more comfortable than an improperly positioned, heavily padded one.
Raise your saddle so you can just barely touch your toes to the ground. If you can put your feet on the ground when stopped, your saddle is too low. When riding, your legs should be almost fully extended at the bottom of your stroke.
Set the top of the saddle parallel to the ground. This allows your "sit bones" to rest on the cushiest part of the saddle. If the nose angles down, you'll slide off the padding; if it angles up, there will be more pressure on your soft tissue.
Slide the saddle along its rails so when the crank arm is in the forward position parallel to the ground, your knees are directly above the pedal spindle.