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j-san = Jason
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Discussion Starter #1
With the arrival of a pair of long Samick BF Extremes (target version), I now have the ability to put together two recurves of equal (AMO) lengths. One is a 17" riser with short limbs and the other is a 13" riser with long limbs. Since they are both 58" long, should I expect to be able to run the same brace height on both bows?

The 17" riser is a W&W RCX17, the 13" riser is a Sky TDX13. Short limbs are TradTech Extreme BF and long limbs are Samick BF Extreme. Both are set to deliver 45#@27". Been busy with work this week so I haven't been able to even string up the 13/longs bow, but I was hoping to do a little experiment with the two and see how much smoother the long limbs would be compared to the shorts and if there was any performance loss due to having a longer limb.
 

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i would say no...

the length of the limb will dictate the size of the triangle that the bow makes.
Shorter limbs naturally give a lower BH.

also the depth of the riser deflex might be different, again giving differed BH
 

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j-san = Jason
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Discussion Starter #3
Some good points, Sid. Eyeballing the risers side by side, it seems the 13" riser has more deflex than the 17" riser. I already have the 17/shorts bow set at 6 7/8" brace which works quite well for it. I am expecting to see a drop in arrow speed with the 13/longs since I would be working the limbs less and likely be running a slightly higher brace height.
 

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Some good points, Sid. Eyeballing the risers side by side, it seems the 13" riser has more deflex than the 17" riser. I already have the 17/shorts bow set at 6 7/8" brace which works quite well for it. I am expecting to see a drop in arrow speed with the 13/longs since I would be working the limbs less and likely be running a slightly higher brace height.
short limbs lower BH, more deflex = higher deflex.

Anyones guess... :)
 

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j-san = Jason
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Discussion Starter #5
The chronograph will decide the winner. I plan to put both bows through the chrono later this week and see what the differences will be. If only I had a draw board, I could try to map out the DFC.
 

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Jason, I can't help you out with the DFC but I do have a chronograph in my range. You are welcome to use it. I'm very interested in what the results would be. You could also test out these new TT extremes I have for you. Scott
 

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j-san = Jason
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Discussion Starter #7
Looking forward to trying the limbs out, Scott! Planing on mounting them on the TDX13 to make a 56" recurve for the ground blind. I've got a chrono at home and will try to get some numbers run on the three different set ups.
 

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j-san = Jason
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Discussion Starter #9
For anyone interested in this experiment, I did get around to stringing up the 13/longs bow and got it roughly tuned in. Immediately, it was evident I needed to run a higher brace height with the longer limbed bow - about 3/4" higher. I also noticed the bow was slightly noisier with more limb vibration than the shorter limbed bow. However, that could be a difference due to one riser being carbon and the other being aluminum.

One difference that was quite noticeable was how much smoother the long limbs were compared to the short limbs. On the 17/shorts bow, I could feel the start of stacking if I pulled it to my ear, which is around 29". The 13/longs bow did not exhibit any stacking at all as far as I could draw. In fact, I think my 27" draw hit the beginning of the sweet spot as it felt less than the 17/shorts and both are set to 45#.

My chrono was misbehaving tonight so no speed numbers to compare, but it launched arrows with some zip.
 
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