[Tvfarmer]

I was shooting tonight and a guy at the range mentioned this. It sounded like BS - but I am new to archery so I thought I would ask.

Based on Identical Bows
a 70#(limbs) bow is backed down 60# is less effective than a #60(limbs)bow set at 60#


His thought is a bow should always be shot at the max of the limbs.

Isn't 60#s - 60#s?

 

[mwaym]

Common theory is............ he's right !!!!!!!!:darkbeer:

 

[MikeK]

Some say it is, some say it isn't.

I would ask Nuts & Bolts' opinion.

 

[Tvfarmer]

What is the rationale? Is it testable - chrono maybe?

 

[Apache]

I'm pretty sure the basic theory is that a 50-60# bow maxed at 60# is transferring all the limb's energy while a 60-70# bow backed down to 60# isn't ...

 

[6bloodychunks]

i dont know for certain either,

BUT,

with the limb bolts maxed ANY bow is quieter !

 

[Hoyt Thompson]

here is a scenario.

Take a Conventional limb bow.
look at a 70# bow backed down to say 60#.
And look at a 70# at 70#.
You will notice that the cams are oriented a little different on the back out bow.
Also the brace height has changed as well causing a lose of speed and energy transfer.
Now look at the 60# bow maxed in weight. The brace Height will be shorter thus transferring every drop of energy allowed by its initial design.

Now do the same with a parallel limb bow.
You will not see much difference between the two.

All of the manufactures rate and test these bows for peak efficiency at peak weight so the bows are intended to perform their best at peak draw weight.

On parallel limb bows you are not going to see much difference in a 70 at 60 vs. a 60 at 60 but the 60 peaked may out perform the 70 at 60 slightly.

At the end of the day does it really matter as long as you enjoy shooting you bow?

 

[Tvfarmer]

Isn't the #age drawn = the energy that is released. Is the KE greater?

 

[Tvfarmer]

here is a scenario.

Take a Conventional limb bow.
look at a 70# bow backed down to say 60#.
And look at a 70# at 70#.
You will notice that the cams are oriented a little different on the back out bow.
Also the brace height has changed as well causing a lose of speed and energy transfer.
Now look at the 60# bow maxed in weight. The brace Height will be shorter thus transferring every drop of energy allowed by its initial design.

Now do the same with a parallel limb bow.
You will not see much difference between the two.

All of the manufactures rate and test these bows for peak efficiency at peak weight so the bows are intended to perform their best at peak draw weight.

On parallel limb bows you are not going to see much difference in a 70 at 60 vs. a 60 at 60 but the 60 peaked may out perform the 70 at 60 slightly.

At the end of the day does it really matter as long as you enjoy shooting you bow?

at the end of the day no it dosen't. I had to ask. Very informative I love physics and would guess that it is a very small performance gain but the bow shooting more quiet may be the bigger advantage.

 

[flintcreek6412]

My simple and non-scientific test of this was to shoot a 350gr arrow out of my 82nd at 70# and I got 338fps. I then dropped to 64# and shot a 320gr arrow and got 332fps. I then dropped to 60# and shot a 300gr arrow and got 329fps.

All the same bow shooting IBO min weight arrow for the adjusted DW and the further from max poundage I got, the slower the IBO speed became. I am sure other factors came into play, but I had a similar experience with my Vulcan and don't remember the numbers.

 

[Tvfarmer]

flintcreek6412's Avatar
flintcreek6412 "I then dropped to 60# and shot a 300gr arrow and got 329fps."

but if you had a bow with 60# limbs set at 60 would it shoot that same arrow at the same speed?

according to "Hoyt Thompson" there wold be an advantage to the 60#limb bow over the 70# Limb bow set at 60#

 

[Ohio Mossy Oak]

read a article

I read a article where they tested a bunch of mid priced bows.. both 70lb max an 60lb max..of the same models..An the Martin Bengal was faster as a 70lb set at 60lb then the 60lb max model was ..I just figured i would pass it along..i shoot a 70lb Bear element set at 59 or60lbs..i hsould bought a 60lb to start with i reckon

 

[automan26]

I have 2 Hoyt UltraMags, one of them has 70# limbs and the other has 60# limbs. The 70# limb, backed off to 60# shoots a bit faster than the 60# limb maxed out. I think the stiffer 70# limb recovers more quickly after the shot than the 60# limb.

Automan

 

[Hoyt Thompson]

according to "Hoyt Thompson" there wold be an advantage to the 60#limb bow over the 70# Limb bow set at 60#

but I also stated that the difference in parallel limbs is not going to make much difference.

 

[Deezlin]

What is the rationale? Is it testable - chrono maybe?

A bow has certain specifications. The specifications are always set at maximum poundage. When you lower poundage then the bows goes slightly out of tune. Yes, it is testable with a good chronograph.

 

[bownutt2]

It has been verified through the engineering and testing specs. (Randy Ulmer testing reports) A bow is at a higher efficiency when shot nearer to its peak weight. The difference is not a large with the newer parallel limb bows with the longer risers, as there is less limb flex than with the older style bows.

We advise our shooters that if they are going to jump above 60# occasionally for game i.e., elk, moose, or distance, they should buy a 70# bow. If not, get the 60# and love it.

Best of luck and good shootin'.

 

[Tvfarmer]

but I also stated that the difference in parallel limbs is not going to make much difference.

Sorry - Didn't mean to mis quote.

 

[Dave V]

60# is 60# but the efficiency is compromised if you're not at your peak tune level.

Try accelerating from a stop sign in second gear. Sorta like that.