Speed - How do you measure it?
 

There is another post on speed. This topic needed to be discussed, not on an advertising level, but with a standards of measurement analysis.

Bow/arrow speed is a relative issue and, like many things in life, should be measured by a standard when comparing different manufacturers. They are not obligated to test methods as you would think and tend to be quite biased when setting THEIR standards.

Allow me to explain how we do our testing. We find one or two manufacturers who meet their advertised speed. There are a few, but very few. We then take another manufacturer and set the bows up exactly alike. We put the bow on our equipment and certify that they have exactly the same AMO draw length (usually we set everything at 30" for obvious reasons). You'd also be surprised at how many manufacturers label a bow 30" and it is actually 31-32". This right here is a 10 fps minimum difference. We use the same draw weight scale, same chronograph (not a cheapy, by any means - Custom Chrono Inc.), and the same arrow weighed on a grain scale that we can also calibrate. The only thing we put on the string is the same nock for all.

What this all does is to set a standard and measure everything against that standard. Now we will find that an advertised bow at 310 fps is just as fast as one that is advertised at 320 fps. How can this be??? The differential is usually found in the falsely advertised draw length or the falsely advertised speed or both.

RE: Speed - How do you measure it?
 

Len

Very good info... but here's a question:

When two different manufactureres claim to have a 30 inch draw... but only one is a true 30 inches... where does the discrepancy originate?

My theory would be the two manufacturers are measuring differently from the throat of the riser? So... one company is measuring from the back of the bow... while others are measuring draw length from the center of the rest mount.

Yes? No?

-DT

RE: Speed - How do you measure it?
 

I understand what your saying Len. It would be nice if all manufacturers would have to state actual draw length. Then state their speeds based on the exact length for a given arrow. Without some kind of regulatory standard through out the industry, it will never happen. That means its up to us as archers and dealers to educate those who aren't aware of these misleadings. I'm sure there are many shooters out there with a 26" draw wondering why their 320 fps. bow only shows 270.

RE: Speed - How do you measure it?
 

DT: The AMO draw length is defined very well. From the throat of the grip to the inside of the nock of the arrow at full draw, plus 1 3/4". If they can measure brace height (a static measurement), the draw length is just the same measurement but done at full draw - plus 1 3/4".

About 8-10 fps for every inch of incorrectly stated draw length. There's your actual 310 when you thought you were getting 320.

RE: Speed - How do you measure it?
 

Is there any other aspect of the testing method that could be manipulated to increase speed?

Then there is the whole other issue of whether or not any given production model bow needs to meet the specs advertised for the model that was tested.

I remember reading on one of the forums on the net that a manufacturer would take the best set of matched limbs, the highest quality cable/string and then polish the axles, etc.... before shooting the "test model" bow through the chronograph.

In other words, it didn't matter what the production bows shot as long as one particular bow of that model shot "X" speed then it was legal to advertise it regardless of whether or not the production models would.

RE: Speed - How do you measure it?
 

Len, why add 1 3/4"?

And -- you may not be willing to -- since this post is in design meant to "enlighten" the public at large, care to list those manufacturers who come closest to meeting their advertised speeds?

RE: Speed - How do you measure it?
 

Frank: You're absolutely right. What do you propose WE do about it? Do you think the industry would submit to an independent test lab like UL?? Doubt it!

MQ1: Good question. I'm not really sure without asking asking someone else; but, I will make a guess. When the AMO standard was originally conceived, I think the draw length had more to do with the length of arrow. By making the draw length 1 3/4" longer than your "true" draw length, this kept the broadheads beyond the hand at full draw.

Regardless, a standard can have eccentric data as long as it relates and maintains the basics of the formula throughout its use.

As far as publishing data like you asked, I'm sorry but that would be industrial/commercial suicide. My family likes to eat and sleep under a warm roof. I hope you understand. Besides that, many manufacturers have taken steps to correct this problem. It wouldn't be fair if their intentions are good or are "in process" of making changes.

RE: Speed - How do you measure it?
 

Len, I figured as much. I thought you had connections to the industry, which might keep you from publishing that info yourself.

Let's just hope that forums like this serve to enhance and educate the public's perception and awareness of the differences which can be found in such "data."

RE: Speed - How do you measure it?
 

Len, thank you again for the information. Just as I have found with many things in life, "things ain't always what the seem"! I would also like to thank you for helping me make the choice on my new bow. This Darton Rampage is got to to one of the best built bows I have ever seen, It may not be the "best" anything, but I tell you I realy think Darton made it with me in mind! It looks realy nice hanging on my shop wall too!

TAKE YOUR KIDS HUNTING AND YOU WON'T BE HUNTING FOR YOUR KIDS

RE: Speed - How do you measure it?
 

Len,

You want me to do something about it? <img src=icon_smile_big.gif border=0 align=middle>...you are a funny guy...<img src=icon_smile_big.gif border=0 align=middle>. I am sure that littl' ol' me can make all of the dishonest manufacturers come clean about their &quot;testing&quot; procedures....<img src=icon_smile_big.gif border=0 align=middle>

Would you like me to end world hunger next? <img src=icon_smile_wink.gif border=0 align=middle>