I have been a avid mountain biker for many years but not until now did I question the Gear Ratios. I have read hundreds of Gear Ratio infos on the web in the past 2 weeks and could not find my answer, I wish you can help. Say, I (175lb and bike is 25lb) am riding 44 teeth front and 11 teeth at rear on perfectly flat road; as I shift rear gear to 13 teeth, I immediately feel lighter (less pedal force) while slow down a bit.

Question: How much lighter in lb? or to be more exact, How much lighter in lb when Gear Ratio drop 1 unit?

All bikers and mathematicians/Physicians please kindly advise. A formula would really help me! Thanks!!