ILF limb questions

[TaterHill Archer]

I have two ILF risers.  One is a 13" VPA riser and one is a Sky Archery TDX riser that I think is a 17" riser.

How do I calculate the limb weight I need to get a 40-45 lb bow with these risers?  I'm not too worried about length just yet, but eventually I want to end up with a 58"-60" bow.  I have a couple of sets of limbs, but to get one set down to that weight, I have to let the limb screws way out.

[McDave]

Limb weight is specified for a certain draw length, usually 28", and a certain riser length, which as not as standard as the 28" draw length, so you have to ask when you buy the limbs.  Generally, limb weight increases about a pound for each inch the riser length is reduced, and decreases about a pound for each inch the riser length is increased. 

So if a set of limbs is rated as 45# @ 28" on a 19" riser, they should be about 47# @ 28" on a 17" riser.  Of course, limb weight can also be adjusted up or down by a few pounds by adjusting the limb bolts on the riser, provided they aren't already maxed or minimized out.

[stevem]

See if this helps-

https://www.uukha.com/en/FAQ-en.php#2

[gnome]

... specifically, what limbs do you have now, and how are they marked.... meaning 25H (rated on a 25" riser), or 17H ...
...extra long 25-H @ 30# limbs will put in in your 40#- 45#range at 13-H, and 25-H @32# on the 17 will get you about the same...
... the average increase of 1 pound draw weight for every inch under 25", in riser length  works if the limb pocket angles are the same...

[katman]

Put the ilf limbs on you have, back bolts out about 1/2 turn and measure poundage at 28. Now you know the weight gain on that riser, as compared to limbs marking As also said prior, watch the limb rating on the riser length. Just to make it more complicated some manufacturers mark limb weight poundage with bolts all in, others half out, so much for standards.