IBO Speed Ranges?

[Konrad]

Most bow manufacturers’ advertising gives IBO speeds as part of their sales spiel. Most of those specifications cover a range (typically 8 fps) or make claims “up to X fps”. Only one company I come to readily advertises a specific number without a range.

Given the IBO specifically states draw length, arrow weight and draw weight, what does this range of numbers represent?

Is this standard deviation, extreme deviation or some other range I am unfamiliar with?

Thanks again,
Konrad

[SPIKER]

This subject is well known to archers that have been around for a while.

While the standard measurements are 70# dw, 30" dl, and a 5gpp arrow (350gr), manufacturers use different methods of getting their ibo speed ratings such as:

1. Using unfletched arrows. Fletching causes drag.

2. Cheating slightly with dl...many so called 30" dl bows will vary from 30" - 32"..there's a built in variable since strings stretch, and many of the same model bows will have different specs based on this.

3. Using "understranded" bowstrings. (less string weight in the right places results in more speed). But, don't try to shoot your hunting/target bow with a 14 strand string for long..lol

4. Speed nocks....weight in the RIGHT places will increase speed.

5. Seemingly, no supervision from any outside agency that I know of. If they can hit a # once, they can use it.

So far Hoyt has been the one company that the average joe can depend on to get the advertised , or better than advertised speed out of, but the Monster series from Mathews is living up to it's ibo speeds as well. Check out the test I did on the Hoyt Vulcan, Monster 6, and XLR8.

(Never mind the APA King Cobra....junk...lol).

Now there's a prime example of an overated IBO listing.

btreviews.proboards.com/index.cgi?board=compounds&action=display&thread=5276&page=3

Now, those are real world tests without any gimmicks.

Don't be fooled by advertising. Search the forums, as I see you are doing, and get info from the guys that are using that equipment, and know how to measure the tolerances.

[ccwilder3]

As a general rule you can subtract 15 fps from advertised claims and be pretty close. There are exceptions.

Glad to hear the Monster is shooting what it is suppose to. Mathews has been one of the most consistent exaggerators on speed in the past.

[SPIKER]

Oct 24, 2010 20:24:57 GMT -5 ccwilder3 said:

As a general rule you can subtract 15 fps from advertised claims and be pretty close. There are exceptions.

Glad to hear the Monster is shooting what it is suppose to. Mathews has been one of the most consistent exaggerators on speed in the past.

Yes, they are. I didn't buy the bow until I shot it through the chrono.

My Hoyts are right on the money also, even a fps more than IBO.

[houseofwhacks]

I have found that Bowtech will generally hit the low end of thier claim and Hoyt will be over.
As Spiker said, most all manufacturers flat out lie.
(He didnt say lie but I did)

I find these practises to be detrimental to sales.
Its not like people dont chrono thier rigs and then post the results!

Worst I have seen (as far as long term and consistent lies) is PSE