Bow Speeds: Fact or Fiction?

[konrad]

Bow Speeds: Fact or Fiction?

I was involved in archery from about the age of nine years old until the beginning of the split limb compound bow technology. Children, career, education and other distractions (including the pursuit of firearms) led me away from archery until five years ago when I again dug out my old PSE bracket wheeled bow, Ben Person alloy arrows and began practicing as a stress relief therapy. Low and behold, I was hooked all over again!

Research on the net (non-existent when last flinging arrows) showed remarkable changes in limb, cam, string/cable, shaft, vane and release technologies. In fact, while I was away, the industry had completely evolved.

Three things emerged as driving forces in advancing archery technology:
1: over-all bow weight
2: arrow shaft weights and materials
3: bow speeds

The last category turned out to be the selling point upon which archery marketers hung their pointed little Robin Hood hats. Two common methods of measurement are commonly used in bow speed advertising, the IBO (International Bowhunters Organization) and AMO (Archery Manufactures Organization). We won’t go into the differences now but most advertising now centers on “IBO speed”. Current advertising using IBO “standards” leave much room for the application of those standards and fudging results. It is widely recognized that many bow manufacturers “stretch the blanket” either by calling 30 3/4 inch draw 30 inches, using lighter than normal strings and/or arrows or by boosting draw weight and still calling it the “IBO standard” of 70 pounds peak. In short, it is virtually impossible for the fellow behind the counter to reproduce advertised speed numbers in his/her clients’ set ups.

The AMO testing standard is avoided like the plague because the speeds, with more realistic arrow weight/draw weight ratios produce much less sexy (slower) numbers.

All of this leads me to an article I read in 35th Anniversary Edition of Archery Business Magazine (also available on-line) entitled “Bow Speeds: Fact or Fiction?” The Archery Trade Association or ATA has a technical board that reviews and attempts to institute industry wide standards that provide the consumer with the ability to conduct apples-to-apples comparisons between similar products. Their latest efforts center on realistic bow speeds using three standards based on 5 grains of arrow weight per pound of draw:
1: 30 inch draw, 70 pound peak weight and 350 grain arrow
2: 30 inch draw, 60 pound peak weight and 300 grain arrow
3: 30 inch draw, 50 pound peak weight and 250 grain arrow

Interestingly, before the discussion was started, letters were sent to all of the bow manufacturers in 2008 and the only folks representing bow manufacturers were Bear, Hoyt, Mathews and PSE.

The way I see it, the ATA standards are easy for the consumer and the manufacturer to understand. Any bozo should be able to set his bow to the ATA specs and then shoot over a chronograph and get the same results as the manufacturer. The way it stands now, the average Joe buys a bow and the local shop is immediately put in the position of making excuses for the client’s bow not performing as advertised. I don’t know about you but whenever a salesman begins dancing, I get the feeling I’m about to get hosed…and not with the garden variety type.

It seems to me that it does no one any good to start a new archer out with trying to explain away a lie. We need more credibility in the archery industry not less.

Of course, those familiar with my previous posts know the next area I think standards should applied are in the measuring of accuracy potential. I know there are work-around solutions for many technical problems for most bows to achieve acceptable accuracy; however, it still seems to me that a basic accuracy test could be applied across the board. From an advertising standpoint, who wouldn’t want to have the bragging rights of “Most Accurate Bow for 2012” in just the same way speed is contested now?

[hughjorgan]

I don't really see a problem with how they market the bows speeds. If you look at the numbers that they advertise, it should be fairly obvious that most people don't have a 30" draw and in the case of Washington in a hunting setup up you won't be shooting any where near the the 350 grain arrow that most manufacturers use to determine the max speed of their bows.

[Old Dog]

Good post Konrad!  I sell bows for a living, and I have to explain the manufacturers exaggerations to every potential new archer.   I make the sale, set up the bow, and then when we take the bow to the lane for the final set-up the customer sees the chronograph.  Naturally they want to see how fast thier new bow is.  I shoot through the chrony, and the bow does a respectable 270 to 280 fps, and the customer wants to know whats wrong with the bow.  How come it isn't doing 325fps?  I've taken to warning them early on that the bow won't reach manufacturers speeds because...  Once again good post.

[MDGrand]

Good post Konrad!  I sell bows for a living, and I have to explain the manufacturers exaggerations to every potential new archer.   I make the sale, set up the bow, and then when we take the bow to the lane for the final set-up the customer sees the chronograph.  Naturally they want to see how fast thier new bow is.  I shoot through the chrony, and the bow does a respectable 270 to 280 fps, and the customer wants to know whats wrong with the bow.  How come it isn't doing 325fps?  I've taken to warning them early on that the bow won't reach manufacturers speeds because...  Once again good post.

Hey Old Dog...

I am happy to hear you say this as I was a little suspect on my speed. Right now I am shooting Martin Firecat TR2 at 67 lbs with a 400 grain arrow including tip and getting 270 FPS.. Since this bow is rated at 345 with a 350 grain arrow I was a bit surprised that I was not getting at least 300 FPS with my set-up.. Fairly new to Archery as I just started REALLY getting into it the last 2-3 years.. .

But I would love to hear the overall reasons why bows, once they are fully set up are not getting the advertised speed.

I know that arrow weight has a lot to do with it, but what are the other causes?

Also.. I was curious as to how bow strings are placed or set and how they effect draw weight. My limbs are cranked down to take advantage of the 70 lb they advertise, however, when measured the pull comes out to 67. I was told this was due to how the strings might have been set up. Can you add any insight to this?.. Just trying to learn.

Regardless, I am pretty extatic about my set up and love the bow overall so I am not changing, but would like to learn more about this.

Thanks!

[Machias]

Great post konrad!!  I had some more typed up but it just would have spiraled into the short range long range argument that always ensues.  So I'll keep it at Great post Konrad!!!   

[huntnfmly]

Good post Konrad!  I sell bows for a living, and I have to explain the manufacturers exaggerations to every potential new archer.   I make the sale, set up the bow, and then when we take the bow to the lane for the final set-up the customer sees the chronograph.  Naturally they want to see how fast thier new bow is.  I shoot through the chrony, and the bow does a respectable 270 to 280 fps, and the customer wants to know whats wrong with the bow.  How come it isn't doing 325fps?  I've taken to warning them early on that the bow won't reach manufacturers speeds because...  Once again good post.

Hey Old Dog...

I am happy to hear you say this as I was a little suspect on my speed. Right now I am shooting Martin Firecat TR2 at 67 lbs with a 400 grain arrow including tip and getting 270 FPS.. Since this bow is rated at 345 with a 350 grain arrow I was a bit surprised that I was not getting at least 300 FPS with my set-up.. Fairly new to Archery as I just started REALLY getting into it the last 2-3 years.. .

But I would love to hear the overall reasons why bows, once they are fully set up are not getting the advertised speed.

I know that arrow weight has a lot to do with it, but what are the other causes?

Also.. I was curious as to how bow strings are placed or set and how they effect draw weight. My limbs are cranked down to take advantage of the 70 lb they advertise, however, when measured the pull comes out to 67. I was told this was due to how the strings might have been set up. Can you add any insight to this?.. Just trying to learn.

Regardless, I am pretty extatic about my set up and love the bow overall so I am not changing, but would like to learn more about this.

Thanks!

peep sites add weight to string/d-loops wich slow down speed also anything else you add to string and when your draw length is less than 30in. you loose 10fps average per inch lost say your draw length is 28in you losse roughly 20 fps larry(old dog) can explain things much better than i he has helped setting up  my bows and spent alot of time troubleshooting probs i had also.good guy

[xXx Archery]

draw lenght + or - 1" will gain or loss 10-12fps.
Lbs. you will gain or loss 2fps per lbs.
arrow weight you will gain or loss 1fps for every 3 grains
and then add a D-loop and a peep -about 5fps

so if you have a bow with a IBO speed of 335
at 28" draw.= about 20-24fps loss
at 65lbs. = about 10fps loss
arrow weight of 390 is 40grains over the IBO of 350 = 13fps loss
D-loop and Peep = about 5fps loss
will shoot 282-285fps

bottom line is
if you have a bow with a IBO rating of 320 and looking at a new bow with a IBO of 350
the new bow will be 30fps faster than your old bow...
hope this helps
 
I wish all bow co. could just get there Draw Lenghts right.

[Old Dog]

Bows speed is rated on the IBO standard of 5 grains of arrow weight per pound of draw weight at 29" draw.  Any extra weight on the string requires more energy to send the string forward.  That includes the arrow.  WA. hunting laws require 6 grains of arrow per pound of bow.  With a 70# bow that is an extra 70 grains of weight that the bow needs to propel forward.  Most bows will lose 1 fps per grain over IBO.  Add a peep sight, "d" loop, and string silencers, and there is no way the bow can reach IBO speeds.  There are accessories to help minimize weight, i.e. magnesium peeps and string stops, but you can't eliminate it.

As to the question about the string set up...yes the way the strings are installed can alter draw weight, and draw length as well.  In your case either the buss cable(s) are too long or the string is too short.  Or maybe the scale you used is off.   Check the axle to axle length, and the brace height to make sure they are in spec.  If not, then something has shifted.  It's common for strings and cables to stretch a little during the first 100 or so shots.  The bow may need to be serviced.

[mtbiker]

draw lenght + or - 1" will gain or loss 10-12fps.
Lbs. you will gain or loss 2fps per lbs.
arrow weight you will gain or loss 1fps for every 3 grains
and then add a D-loop and a peep -about 5fps

so if you have a bow with a IBO speed of 335
at 28" draw.= about 20-24fps loss
at 65lbs. = about 10fps loss
arrow weight of 390 is 40grains over the IBO of 350 = 13fps loss
D-loop and Peep = about 5fps loss
will shoot 282-285fps

bottom line is
if you have a bow with a IBO rating of 320 and looking at a new bow with a IBO of 350
the new bow will be 30fps faster than your old bow...
hope this helps
 
I wish all bow co. could just get there Draw Lenghts right.

Wow, Cory just just quoted the exact setup of my Athens Ibex.  AND it chrono'd 282!!!   

[carpsniperg2]

Cory is the man and knows his stuff Makes a wicked bow string to

[Matt]

Look at it this way.  IBO speed rating is the bows potential.  Serious 3-D shooters will be the closest to this.  Speed bows today are way different than speed bows just 10 years ago.  Manufacturers have made them a lot more forgiving and shootable.  But one still has to tune them and their arrows to stay accurate.  A good spec sheet means nothing when it comes to shooting a bow.  If it fits like a glove and you can hit what you are aiming at then buy a good rangefinder and don't worry about the speed.

On a side note.  The birth certificate that Bowtech attaches to the bow is the best thing going for this conversation.  It is THE TRUTH.

[Lowedog]

I actually don't see the problem with IBO rating.  It is very easy to understand IMO.  There are many calculators online that will show what speed a bow should shoot with deviations from IBO standards. 

[Todd_ID]

I actually don't see the problem with IBO rating.  It is very easy to understand IMO.  There are many calculators online that will show what speed a bow should shoot with deviations from IBO standards.

Yeah, but there's too much leeway in the process.  I watched a company bring a bow to the shop to do the test runs.  It took over an hour, and they now advertise the highest reading that they saw.  The rest were 5-20 fps slower.  Draw weight was 2# high, draw length was .375" long, string was purpose-built to only survive a couple shots then changed out, limbs were changed after 10 shots, high-wrist grip was used to eek out more draw length, no nock indicator of any kind just a sharpie marker.  A 1/10 turn on one limb bolt sent the bow into hyperdrive on the one high reading they got, and I think it was more a chrony error.  The rest of the shots with that same setup were 5 fps less at least.

But it still passed, and lots of people now own them thinking they should be getting that speed.

I think the testing standard should be set so that an average archer can duplicate the speed.  70# and 30" and 5 gr/lb is fine, but make them use a peep and nock indicator of some kind and give zero leeway in the measurements; then take an average of 25 shots with that setup.

[konrad]

Well said, Todd.

Another place I think accurate advertising would help tremendously:
Speeds at 50, 60 and 70 pounds, 30 inches draw and 5 gpi should be posted for every bow (with at least 20 grains of weight on string for nock set, peep and d-loop).
When prospective buyers see the marginal speed differences between 50, 60 and 70 pounds of draw force, perhaps they would opt for a rig more manageable and therefore produce an archer with a higher probability of accuracy and a higher degree of satisfaction.

For many years the magnum rifle craze raged and many folks were turned off to big game rifles because they were unable or unwilling to learn how to deal with the magnum recoil of those firearms. The neophyte archer who is over-bowed struggling with technique will never reach their potential due to fatigue, injury or disappointment.

[Lowedog]

I gree with Todd that there is too much tolerance allowed for IBO rating.  Most of the big manufacturers are very close though on there IBO ratings.  Those that are stretching the deviation from standard in order to up their claimed speed are soon exposed because of online forums. 

Again, there are many calculators online that will be very close to what a given setup will shoot. 

If you want to know exactly what a bow shoots coming off the assembly line then I suggest you look at Bowtech because as Matt said they have it written right on the birth certificate. 

The best thing you can do when shopping for a new bow is to shoot every thing you can get your hands on and don't worry about what the IBO rating is.