See the following for Hammer Strength HD Air Bike Seat Adjustment Instructions
A properly adjusted seat is important in any bike-oriented exercise activity. If the seat is too close, excessive strain will be placed on the knees and quadriceps muscles. If the seat is too far, the resulting reaching action will irritate the feet, ankles, hips and knees.
1. Sit on the seat and place the balls of the feet on the pedals. An optimal position allows movement through the bottom of the stroke without locking the knees, shifting in the seat or forcefully extending the hips. The knees should have a slight bend at the point of fullest leg extension.
2. To adjust seat height, loosen seat adjustment knob, hold seat, then raise or lower.
CAUTION: Do not attempt to adjust the seat while pedaling the bike or sitting on the seat. Doing so may cause injury or result in an uncomfortable workout.
3. Tighten seat adjustment knob.
4. To adjust seat horizontally, unlock horizontal adjust lever by rotating counter clockwise.
5. Adjust seat forward or backwards as needed. The knee of your forward-facing leg should be positioned directly above the center of the pedal. If this does not correspond to your bike‘s setting, align the horizontal saddle adjustment to the front or rear in order to attain this seat position.
6. Lock horizontal adjust lever by rotating clockwise.
See the Hammer Strength HD Air Bike Owner's Manual for more information