You might try adjusting the seat height. When you are sitting on the seat your right foot on the pedal, extend it to the lowest point of the rotation from here, there should only be a slight bend at the knee. Your leg should look as if it is close to full extension but not quite. However by the same token it should not be locked out straight, this would indicate the seat is too high. However if you have great pressure on your knee, i would assume the seat is too low. Try asking some one at the gym if they can help clarify what I am explaining to you.
