Does a higher brace height make for higher draw weight at a given draw length?

geoffretired

Supporter
Supporter
Yes, short bows and long arms will test limbs to their limits; more so with shorter strings.
I agree with your brace height v energy graph. I think I described it as power stroke and average draw weight/force.
Long string gives a long but light push to the arrow; the medium string gives a shorter but stronger push; very short string gives high force but very little power stroke.
My thoughts are, like yours, a curve that flattens out ( and turns downwards) with a peak at some part but not at the end.
Without a chrono???? I can't see any way that the theory could be wrong, I just can't guess where the high spot would be. I would guess it's around the BH that is recommended by the manufacturer. That may not be scientific but if we have to prove everything we say before we say it; life would be very tedious.
 

Del the Cat

Well-known member
Geoff, the only way to get good data is to do it yourself, which is no prob on a modern recurve.
You could easily plot draw weight at a constant draw length (maybe a tad short for safety), taking brace up in 1" increments using an adjustable string.
E.G a long string threaded through a loop of Ali' or an old bearing etc. It's what I do when tillering a bow.
https://bowyersdiary.blogspot.com/2014/06/yew-primitive-braced.html
Not a good idea on a wooden bow though except over a very limited range.
Del
 

geoffretired

Supporter
Supporter
Del, you are right.
I have used some of the data already posted on here and feel it proves a point.
One of the things I have done is to use Pythagoras on the triangles you see when you draw a bow. With a shorter string, every inch of draw, brings the two string loops even closer together than with a longer string.In other words every inch of draw on a short string puts a greater bend in the limbs, than that with a longer string. I guess the readings every 1" are not so easy to detect, but by the end of the draw with each string, the differences in totals should be detectable.
Perhaps that goes some way to explaining why my other post is flawed. With the shorter string returning from full draw, each inch is more than the expected 2Lb, so the weight reduces to 0lbs sooner i.e. at a higher brace height.
 
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