# How many pounds per inch over 28"?



## limbwalker (Sep 26, 2003)

Yes, 1.5-2.5 ppi is common. Usually 2 but it depends on a lot of factors. 

I don't want to try and predict where any particular set of limbs is measured on which riser, on which scale.

It really doesn't matter if you're shooting 45# or 48# (provided you can handle the weight). It's really what tunes the arrows you have.


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## baller (Oct 4, 2006)

limbwalker said:


> Yes, 1.5-2.5 ppi is common. Usually 2 but it depends on a lot of factors.
> 
> I don't want to try and predict where any particular set of limbs is measured on which riser, on which scale.
> 
> It really doesn't matter if you're shooting 45# or 48# (provided you can handle the weight). It's really what tunes the arrows you have.



Unfortunately I don't have any arrows at the moment so I'm trying to guess what arrow spine/limb weight will give me the most room to make adjustments to find a tune. If I remember correctly the last set of NPXs I had were 500s at 30" nock to end of point so approx 29.5" nock to carbon and I had to bottom out 40s to get them to tune (i think around 47.5-48#) but my memory is a little hazy at best.

Was thinking either a 500 at 29.75 for 47ish or a 550 at 29.75 for 42ish.


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## limbwalker (Sep 26, 2003)

Always a tough call until you get the bow set up and actually shoot arrows. I can tune 400's, 450's and 500's from my bows depending on how I set the tiller bolts and set up the arrows, and which arrows I'm using. I do it every year going from indoor to outdoor to field. So I'd say start with the weight you think you can handle, then borrow a few arrows and see what's going to be the most likely spine to tune, then go from there - knowing you have a LOT of adjustment even after selecting and trimming arrows (points, fletching, nock options, draw weight, string build, etc.)


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## zal (May 1, 2007)

This is sort of average I've measured over few limbs I've had (70" on 25" riser):

29: +1,8#
30: +2,1#
31: +2.3#
32: +2,5#
33: anything from 2,6# to 3,2#

Depends a lot on the limbs, riser deflection and other variables. Those are with Hoyt riser I had, I tried some with a Samick and it's completely different. Generally on my 32 5/8" draw I get anything from +8# to +11#.


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## Stash (Jun 1, 2002)

For a bow that has a straight draw force curve, subtract the brace height from 28" and divide by the weight at 28". That gives you the increase in draw weight per inch of draw. 

However, bows don't have a straight draw force curve. Most will stack to some degree past 28, 29, 30", depending on the bow design, length and construction. Never hurts to have a cheap digital scale handy so you can know for sure how much you are in reasing gour draw weight when increasing your draw length.


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