I see on bows all the time is says __% let off. For example the Mathews Z7 Extreme says 80% let off... I know Im an idiot, but, what does that mean?
A 70lb bow with 80% Let-off means at full draw your only holding 20% of the bows weight... Which in this example would be 14 lbs your holding at full draw.
The letoff only happens when the cam or cams are rotated. To get the cams spun around to the let-off you need to pull back the initial draw weight. The let off is intended to allow you to hold a drawn bow longer. If a 7 year old can draw 70# then that kid is a beast! So a bow with a greater let-off percentage wise means you'll be able to hold it back longer without getting tired.