[Hank D Thoreau]

I recently had the opportunity to compare two bow setups for Gary McCain: Formula F7 and Formula Quattro limbs on identical HPX risers. Gary had noticed differences between the earlier F7 and the more recent Quattro. I wanted to see whether a quantitative assessment match what Gary observed. I have also been interested in these limbs for some time. I had heard that these limbs were attempting to achieve a Border-like smoothness with a more conventional geometry. I wanted to see what the quantitative assessment showed in this regard. Since these bows are virtually identical, except for the limbs, this represents a good, comparison test case.

I will start by showing the main panels for each bow, and then show comparison charts.

 

[Hank D Thoreau]

 

[Hank D Thoreau]

It should be noted that both limbs had limb savers attached, which are included in the weight measurements. There was a slight difference in brace height for the Quattro which should only have a small impact on the results.

(Correction: Both were 73% efficient. There was a overwrite in my program. Charts have been fixed) The F7 were the more efficient limb at 81% compared to 77% for the Quattro. However, both numbers are very high for my measurement method. While the Quattro stored more energy, and were faster, the F7 were more efficient. This efficiency advantage appears to be a consequence of the smoothness at the end of draw where the F7 flatten out at about 2.2 pounds per inch from 29 to 32 inches, compared to the Quattro that start to stack after 27 inches.

The energy per weight on the fingers is pretty similar for both limbs, neither breaking 1.0 until 32 inches.

The Quattro were faster at 199 fps and also had lighter limb tips at 80 gr using the two scale measuring method. This is compared to 195 and 86 for the F7.

The smoothness curves is where it gets interesting. The Quattro have a remarkably flat first derivative (smoothness) curve from about 18 inches to 27 inches. This is unique profile for conventional recurve limbs that I have measured. After 27, they start to stack, which is quite early in the draw cycle. The F7 do not stack all the way out to 33 inches. As mentioned before, they run about 2.2 pounds/inch from 29 to 32.

There is a clear difference between the limbs. The F7 are smooth at the end of the draw, while the Quattro are smooth during a large portion of the draw prior to release. The smoothness curves cross at 29 inches, after which, the F7 pull less pounds per inch of draw. So the choice is between a smoother more efficient limb, or a slightly faster but less smooth limb. You might be able to up the weight on the F7, maintain a similar holding weight at full draw, and match the speed of the Quattro, while maintaining the smoothness of the F7. It would be interesting to try that out.

Thanks to Gary McCain for making his bows available to me to test.

 

[2413gary]

One thing I left out is the F7 limbs are carbon glass and Quattro's are carbon wood

 

[Hank D Thoreau]

I fixed the chart in the original post to reflect wood for the Quattro.

 

[Kiwidude]

Wow, I wasn't expecting that ! For about a hundred bucks more, you would think that the new and (supposedly) improved Quatro's would smoke the F7's...

"Hoyt engineers set out to design the most torsionally-rigid, accurate, high performance limb in our history. Not only did they succeed, they absolutely broke the limits. Quattro series limbs feature more torsional stiffness than any commercially available limb made today. More speed. Less noise and vibration. A feel like no other, and responsiveness (are they talking about a negative response or a positive one ?) that is instantly obvious on the first shot. The new technology leader."

From the Hoyt website.

 

[Hank D Thoreau]

Here is a comparison of the Hoyt Quattro to a set of PSE ProElite (rebranded Win Win Winacts). The ProElite are representative of a limb with a conventional recurve geometry. Notice the difference between the curvature of the ProElite curve during the middle of the draw, compared to the flatness of the Quattro.

 

[Hank D Thoreau]

Here is a comparison of smoothness between the Quattro and Border HEX6 limbs. The HEX6 are recognized for their leading edge smoothness resulting from a radical recurve design (often referred to as a super recurve). I have included a comparison of energy per weight on the fingers. It is interesting to note that the Quattro curve tails off starting at 28 inches, while the HEX6 continues to climb. This means that the HEX6 are storing energy more effectively at 28 inches and beyond. While the Quattro are still far from the Border in terms of smoothness, they appear to be different that a conventional recurve design (provided the flatness of the curve is not an artifact of my measurement).

 

[Kiwidude]

Hank, I'm currently debating 45# Hex 6 limbs or 45# Hoyt Quatro/F7's for my 21" Hoyt riser. My draw length is very short (26")...so would there be much of a difference depending on which of the aforementioned limbs I choose ? From how I see it, the Hex limbs really start kickin' in the performance dept. when you hit those longer draw lengths ?

Thanks ! You're a godsend.

 

[Hank D Thoreau]

Wow, I wasn't expecting that ! For about a hundred bucks more, you would think that the new and (supposedly) improved Quatro's would smoke the F7's...

"Hoyt engineers set out to design the most torsionally-rigid, accurate, high performance limb in our history. Not only did they succeed, they absolutely broke the limits. Quattro series limbs feature more torsional stiffness than any commercially available limb made today. More speed. Less noise and vibration. A feel like no other, and responsiveness (are they talking about a negative response or a positive one ?) that is instantly obvious on the first shot. The new technology leader."

From the Hoyt website.

To be fair, I did not test torsional rigidity or stability. Also, the wood core Quattro I tested were 4 fps faster than the foam core F7. I guess we really need to understand what revolutionary performance really means and how to properly measure it. Ultimately, it is points on the scoreboard for a target bow.

 

[Hank D Thoreau]

Hank, I'm currently debating 45# Hex 6 limbs or 45# Hoyt Quatro/F7's for my 21" Hoyt riser. My draw length is very short (26")...so would there be much of a difference depending on which of the aforementioned limbs I choose ? From how I see it, the Hex limbs really start kickin' in the performance dept. when you hit those longer draw lengths ?

Thanks ! You're a godsend.

I was testing 70 inch bows. For a shorter bow, everything that happens in the draw cycle from 28 inches and above for the Borders, will happen earlier. It all depends on the length of your riser and limbs relative to your draw length.

 

[2413gary]

I like the 4fps and the softer feel of the wood after the shot

 

[Hank D Thoreau]

I like the 4fps and the softer feel of the wood after the shot

Wood is definitely under rated. I like shooting wood. It is also more economical.

 

[Humdinger]

Interesting stuff! Im starting to understand all this...

 

[kenn1320]

I was testing 70 inch bows. For a shorter bow, everything that happens in the draw cycle from 28 inches and above for the Borders, will happen earlier. It all depends on the length of your riser and limbs relative to your draw length.

Hank your first post states medium limbs on a 25" riser, these are 68" bows. I wouldnt expect them to be smooth out past 29", that is the transition point between medium and long limbs. What length are the Border limbs you compared here?

 

[2413gary]

I can Guarantee its way over this ******** head

Interesting stuff! Im starting to understand all this...

 

[Hank D Thoreau]

Hank your first post states medium limbs on a 25" riser, these are 68" bows. I wouldnt expect them to be smooth out past 29", that is the transition point between medium and long limbs. What length are the Border limbs you compared here?

You need to look at the shape of the curves rather than the absolute numbers. Notice how the Quattro first derivative curve quickly flattens out in the middle of the draw cycle, and then starts to stack. The HEX6 never flatten out. They continue to drop until you get near the string lift point, which is much further out than with conventional limbs. They do not start to stack until much later in the draw. The beauty of the first derivative curve is that you are comparing shapes rather than numbers. Shorter bows will just compress the curves. The lift point probably shifts about half the difference if bow length, which would be 1 inch. So even with the chart of energy per weight on the fingers, the drop off near full draw begins earlier.

This is not a Border to Hoyt comparison thread. I use Border as the standard when looking at smoothness. They are the gold standard in this area. I will try to use the best comparison candidates when possible. I am going to take a look at the Hoyt Formula limbs compared to some other high end limbs I have tested, such as MK Korea in the Formula configuration. I will post those later tonight.

 

[kenn1320]

Hank I dont understand all the numbers, just was commenting that you said you were testing 70" bows, but you were not. Also pointed out that medium limbs are not expected to be smooth with no stack at 32" or whatever you pulled them too. If the F7's didnt exhibit stack then Im impressed. Its also nice to see a big difference between the (2) Hoyt limbs, as Im sure there are posts on AT that claim the Quatro is likely a rebadged F7 and youve shown that isnt the case.

 

[Humdinger]

I am going to take a look at the Hoyt Formula limbs compared to some other high end limbs I have tested, such as MK Korea in the Formula configuration. I will post those later tonight.

I want to see this!!!!!!!!!!

 

[Hank D Thoreau]

Here is a comparison to the MK Korea Mach 3 limbs. It turns out that they are ILF. I thought I had tested some Formula MK Korea limbs. These are some of the highest performing limbs I have tested, and Humdinger and his fiancée use them. The MK Korea limbs are 45 pounds so the first derivative curve will be shifted up, but since the bow is 68 inches, the horizontal axis will not be shifted. The second chart is energy per weight on the fingers and is great in that it automatically compensates for differences in bow weight. You can see from the first chart that the MK Korea limbs behave as expected for a conventional shaped recurve, just like the PSE ProElites in the earlier chart. The minimum, however, is shift further to longer draw than I typically find for a 68 inch bow. Compare the minimums of the F7 and MK Korea. Energy per weight on the fingers is consistent for all three bows, showing that they all have a similar ability to store energy, even though the MK Korea are 9 pound heavier.

Kenn1320, you just gave me an opportunity to bring up good point about these curves. I need to the feedback so that I can improve on my explanations. Keep the feedback coming.