BRACE HEIGHT - RECURVE

[Neil Turner]

Having trouble determining which is the best brace height for my bow using the sound of the bow. Have been reading about an alternative as follows:

Set at lowest height recommended by manufacture and at about 50m shoot 18 arrows or so and plot the arrows to determine the vertical height of the group. Increase brace by 1/16 or 1/8 inch and insure nocking remains constant, adjust if required. Shot another 18 or so arrows at the same sight setting at new brace height and plot to determine vertical height of group as before. Continue until you reach the highest brace height recommended by the manufacture.

The brace height that has the highest vertical group height will be the best to use as it means that the energy transfer from bow to arrow is at its maximum (bow should be at its quietest).

Does this sound sensible. :confused

[Eberbachl]

mmm...makes alot of sense to me, sounds far more reliable than using the sound of the bow solely as the method of setting the brace height.

Having said that I must say that I really know squat about shooting recurve, so don't pay any attention to me :D

perhaps another recurve shooter has something to say.

P.S...where did you find the information?

[Neil Turner]

Luke, found the info at the Texas State Archery site http://www.texasarchery.org[URL2]Texas State Archery Association in the document section under the Murray Guide (Archers Reference Guide "Recurve"). Some archer by the name Marcel van Apeldoorn suggest this particular method.

I tried it today, and the plot indicated that I should use a higher brace height than what I currently do. So I retuned the bow using new brace height and will see how it goes over the next few weeks. Mind you my groups are not the best. :D

[Marcus]

If you see my Dad on the weekend it would be worth while asking him what to use. He shoots recurve every so often and can set them up pretty well. Don't quote me but a higher brace hight would make you arrow stiffer I believe. So if your bare shaft is going right then put your brace hight up.
Sounds like a method of group tuning. There is an article in the Glade (a past one) on group tuning by Jay Barrs (kinda a recurve legend), I'll try and bring it down for you to read.

BTW it sounds sensible, but doesn't sound 100% right to me. You hear statements in this sport that may sound right, but if you can find another way of looking at it, come out wrong. One in compound is "A high nocking point is better because it gives the arrow a dirrection" I don't buy that for a second.

I'll have a read around and get back to you.

[Jim Park]

The correct brace height is determined by the natural frequency of vibration of the arrow. Following the release, the arrow flexes due to the string coming of your fingers to the side. For a right handed archer, the nock first moves to the left. Following that, the arrow first straightenes and then bends nock to the right. After that it again straightens, and it is at this time that you want the nock to leave the bow string. The arrow then flexes nock to the left as the fletches clear the bow.
What this means is that you have to select the natural frequency of vibration of the arrow such that the fletches are to the left as they clear the bow (it is not actually the stiffness of the arrow that needs to be correct, but the natural frequency - the stiffness is just one of the parameters that affects the natural frequency). Given that you have selected the correct natural frequency, the correct string height is then set as above. The reason the bow is "quietest" when the string height is correct is because at this point the nock comes cleanly off the string rather than having a side force imposed on it by the arrow being bent rather than straight at that time. Besides sounding quieter, the bow will also tune more easily with that string height, and the groups will be tighter.