# 'Speed nocks' on a bow string: true or false?



## tjwood (Oct 30, 2006)

Hi,
A couple of years ago I purchased a Hoyt Ultratec. It had a new string on it so I only replaced it at the end of last season. I asked the dealer who made the new string for me what the 'lumps' on the string were just below each of the cam serving. He said that they were 'speed nocks' and said he'd make sure he put them on the new string as well. Being fairly new to the game I didn't argue. I asked him what they were for but he couldn't tell me. Each 'speed nock' was covered by heat shrink tubing and when I cut it off I saw that each 'speed nock' unit was actually made up of three brass nocking points crimped close up to one another.
So my questions to all you intelligent guys out there are: 
Are those things really called speed nocks, or have I fallen for a bit of archery bull? 
What do they do? 
To my limited brain, having all that extra weight on the string would slow it down, not speed it up?? 
Also, how do you know how many brass nocks to put on the string? Is it set by the number of strands, the string material or what?
I was tempted to take them off to see what would happen but because I'm unsure what they do I didn't try it just in case it damaged something.
Thanks in advance for your help.
Tony


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## FSL4ever (Mar 27, 2006)

Happy Thanksgiving!

The theory behind them is that they dampen extra vibration at certain frequencies that otherwise takes away from arrow speed. Think of an open guitar string versus one pressed down to the fingerboard: instead of resonating at all possible frequencies (defined by the length of the open string), the string resonates (sounds) higher because the lower frequencies are eliminated by shortening the string. On a bowstring, the speed nocks are similar -- they don't shorten the string, but they do act to prevent resonance or ringing at some frequencies. (They form a band-stop filter, for those of you who are electrically-inclined.) In theory, the energy that would have gone into that ringing goes into ringing at "good" frequencies that add to arrow speed.

I say "in theory" because tuning the speed nock position is difficult -- the distance along the string (e.g., how fa in from where the string meets the cam) determines the frequencies it damps. Put them in the wrong spot and they can damp the "good" frequencies and slow down the arrow. I used some on mine and found it took a lot of trial and error to place them right, as well as an accurate chronograph. Hoyt of course has already figured out the optimum spot, so if you change strings or pull them off for repairs, be sure to put them back in the same place.

Hope that helps.


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## TOOL (Apr 11, 2006)

Truball speed balls (which is bsdically the same) has given me a solid 10 fps more on each of mine.


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## TMan51 (Jan 25, 2004)

Do they do anything?

Yes, they reduce vibration frequency, if you're lucky, at a primary node.

Do they affect speed?

Yes, but you'll need a chronograph, and some time to establish how much, and the optimal point on the string.

Are they worth the effort?

Not on a target bow most of the time, at hunting ranges, or 3D distances, you'll probably never notice the difference.


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## The Yankee (Nov 23, 2005)

As other people have already explained you will need a chrono and spend some time sliding them up and down your string to get the optimum location for them. Before the string companies and bow manufacturers started putting these on their strings most of the serious shooters would tweek every bit of speed out of their bows that they could get. The speed buttons along with many other little tricks would end up giving them 10 to 20 fps more than someone who did not know how to tweek their bows. This would help a considerable bit on their kinetic energy, and the flatness of their shot. If someone is making a new string for you just keep the old string handy and measure where those nock buttons are on it then put them in the same place on the new string.


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## tjwood (Oct 30, 2006)

Thanks guys. Guess I'll just take the advice of making sure that they're always put in the same place on new strings. The 'science' of this stuff is just a bit too daunting for me so I'm not going to meddle (and I don't have a chrono). At least I now know I wasn't being spun a yarn about what they were called AND now I know what they're actually for.


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