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Main Boards => PowWow => Topic started by: HcSmitty on January 16, 2011, 10:01:00 PM

Title: lbs per inch.
Post by: HcSmitty on January 16, 2011, 10:01:00 PM
Im thinkin very seriously about ordering a ne bow.  But in decideing what weight to have the bow at Im kinda winderin how may lbs per inch of draw is smooth.  Ive heard that 2lbs plus per inch is noticeably less smooth.  Does it vary from recurve to longbow?  Can anybody tell me about these things?
Title: Re: lbs per inch.
Post by: Whip on January 16, 2011, 10:40:00 PM
The force draw curve, even on a trad bow, is not a completely straight line.  A bow will gain weight a little quicker early in the draw, then a little slower toward 28 inches or so, and then start gaining quicker again somewhere beyond that.  (Where it starts to feel like it is "stacking")  That curve will vary slightly from one bow to another based on limb design.

But the amount it gains per inch is more a function of the draw weight of the bow than anything else.  A heavier bow will gain more pounds per inch.  

As an example, a bow with the string 8" from the the back of the bow while at rest, (about a 6 1/4" brace height) must be drawn an additional 20" to reach 28".  So a 40# bow will gain an average of 2# per inch.  A 60# bow will gain an average of 3# per inch.
Title: Re: lbs per inch.
Post by: HcSmitty on January 16, 2011, 10:43:00 PM
well how much of a difference can i feel in the 2lbs vs. the 3 lbs?
Title: Re: lbs per inch.
Post by: Stumpkiller on January 16, 2011, 11:00:00 PM
33%  ;-)  You'll notice the 20# in draw weight much more.

A 50# bow at 28" will require the same effort whether it's smooth or not so there is no 2# vs. 3# to judge from.  It's where the weight per inch changes over the length drawn that changes how a bow feels.  A 56" bow may require 3# to get from 27" to 28" while a 64" bow may only require 2#.   Monleying with brace height can also alter the feel (a bow with a low brace height tends to feel smoother because the weight  is the same but spread over a longer distance).

Smoothness would be a relative judgement of a bow that gains weight evenly.  A bow that pulls initially hard and gets less additional weight per inch drawncan feel very smooth.  BUT, if it starts to stack up in the last inch or two can be a nasty bow for the shooter.
Title: Re: lbs per inch.
Post by: Bowwild on January 17, 2011, 08:50:00 AM
Excellent question!  Very thoughtful responses by Whip and the bane of stumps!

Of all my recurves my Predator feels smoothest. I don't know why and it may be my imagination?  These recurves are all between 41-49 pounds (most 47-48) at my 26" draw. They are 56"-62" (most 58-60")long. The predator is 47# ant 16" and is 60" long.

Of course all these curves are lefties so the woods in my bows were all taken from the smoothest part of the tree. (I like to gig frogs too!)