He said the old string is 18 strands. Didn't say what material. But with it the bow is shock free.
My take is this: Any material be it Fast flight or dacron isn't completely stretchless. The less number of strands the more stretch at the shot. String stretch compromises the efficiency of the bow by not allowing the limbs to stop cleanly at the end of the powerstroke while transfering the energy to the arrow. This lost energy is felt as hand shock. With a low strand count string whatever is gained by reducing the string mass is lost by stretch. I have personally never seen a speed increase going to a skinny string.

No he didn't mention the material of the thick string.  But I wouldn't see the point of using 18 strands of anything beside Dacron.

18 strands of bcy x is equal to just less than 13 strands of D97. I've tried several strings with less and see no point in using less.

And 18 strands of Fury or 8190F would be even smaller.

I've put SBD 8 strand strings on most all of my bows and it made them better. One bow it did not. I don't know the science behind it but that one bow wears a thicker string now and the others wear SBDs.

IMO, it's more about the added finger pressure one uses when first shooting a skinny string. Take some time w/ it and get the feel of the skinny string and things will get back to normal.

BCY-X, 8190 Universal, 8190F...these all would work great with 18 strands (or more).  Very small diameter threads.

In fact BCY recommends 24 strands for BCY-X and 8190. 18 strands for 8125G.

Also this is taken directly from BCY Q&A page:
"Note also that at a certain point not too far below the manufacturer"s recommended number of strands, it is quite likely that the archer will notice an increase in vibration directly after release because there is not enough mass in the string to absorb the "elastic energy" that occurs when the arrow is released."

In the beginning, Fast Flight, 20 strands were the standard, Black Widow was the first to test the waters!

I also talked Dale Karch into offering 18 strand, f.f. when he took over 3 Rivers!

I' m sure they are also offered thru Kustom Kings catalog, too.

I think different bows, different shooters, different arrow weights all will affect how a string works with any given bow. I have 8-strand skinny strings on most of my bows because I started out buying SBD D-10 strings and liked them. I recently put a somewhat thicker BCY-X string by Chad (LBR) on one of my bows and am completely happy with it also. I will continue buying from both makers and personally can not feel a difference. Both work great, don't stretch and improve the performance of all of my bows.

The one comment I keep hearing and can't quite understand is the added pressure a skinny string places on your string fingers. There is no place where your string fingers contact the string - skinny or fat. If the serving is sized to fit the arrow nock, it will be the same diameter regardless of what string is underneath.

???????

QuoteOriginally posted by katman:
Might try adjusting brace height a little.

I am sensitive to hand shock; skinny strings have never contributed to shock in my experience. But I have always had to re tune.