Limb length and draw weight

[Thunk]

Now that my draw length has increased to a magnificent 30" I need to change from 68" limbs to 70". I'm being told by some people that in going to a longer limb I should also increase the draw weight by 2lb because the extra length will make the bow easier to pull. I'm not convinced - surely 36lb limbs are 36lb limbs, whether they are made in 68" or 70". Or am I being thick?

[Shirt]

They're talking out their arses.

40# is 40#, regardless of limb length. E.G, my 70" 42# G3s wound up to feel the same as my 68" 40# Vectors gives me about another four pounds because they're smoother limbs. It is NOT because they're longer.

Another comparison - my 68" 40# Vectors felt a hell of a lot smoother than the 70" 43# Codispoti limbs I have on my GM despite the full draw difference being just that three pounds.

[Big Boy Blue]

Shirt is right, the weight being held on the fingers will not change. The string angel going through the fingers will change as there will be less pinch with the longer limbs.

[Thunk]

Oh, that's what I like about this forum! Seek and you shall find..Speak, and an answer shall be given unto you! Thanks guys! I thought it was a load of old rubbish, but it's nice to have second opinions!

[Bald Eagle]

I think what "they" mean is a 70" limb @40lb will feel smoother to draw than a 68" limb @ 40lb. Your arrows will go faster off the 68" limbs because the cast of the limb is better, ie, not as forgiving as the 70".

[JohnK]

As for the speed difference, it's not as much as you'd think.

A respected US bow designer who I've been lucky enough to meet and correspond with told me about the tests he ran to investigate this subject. With all other factors being equal (draw weight, draw length, arrow weight, etc.) he tested 4 different bow lengths for speed - 64, 66, 68 and 70in. The limbs were identical draw weights, but different lengths.

The difference in speed between each set up was 1 foot per second (i.e. the 68in set up was 1fps faster than the 70in set up).

Now, if I was hovering around 30in or just under, that would be enough to decide me on the longer limbs for the extra smoothness. However, I'm hovering around just under 32in at the moment, so my next set of limbs will probably be 71in

[Little Miss Purple]

I have 66" limbs with a question above whether I should've used 64" limbs (too late now!!) - I did have 68" limbs but I just couldn't get the power out of them as they were too long. Does this imply that the length / weight ratio does matter??

[JohnK]

Originally Posted by Little Miss Purple

I have 66" limbs with a question above whether I should've used 64" limbs (too late now!!) - I did have 68" limbs but I just couldn't get the power out of them as they were too long. Does this imply that the length / weight ratio does matter??

Maybe.

However, when I started shooting at my current club there was a lady archer there with a draw length that suggested she needed a 64in bow. However, she'd taken a shine to a 70in Yamaha EX Alpha that a fellow club member was selling, so she shot that. It was really weird watching her shoot with such a long bow, but pulling somewhere in the mid 20lb range she could shoot well at all distances. As I recall, she reached Bowman class before she gave up shooting to start a family.

[SLOWHAND]

I have just changed from long Synergys to medium G3's with the intention of getting a little more speed for the outdoor season. Now before I had personal experience of doing it I would have agreed with all of the above comments but with both sets of limbs set to 41# at the clicker the shorter limbs definitly feel heavier and they are not as forgiving. Whether this is purely subjective I'm not sure myself yet (my muscles are certainly telling me that I'm pulling more). Having mentioned the negatives with shorter limbs I have to say that in the three weeks I've had them I've shot two tournament pbs' (594 portsmouth and 575 Fita18). Given your circumstances I think I would go for the long limbs but if possible give them both a try if you can.

[Big Boy Blue]

The weight will still be the same, what will change is how the limbs store and then transfer the energy. I think it is this that makes them feel different.