Mark,
RUBBISH!!! A bow will not break by an overbuilt string. I've not heard anything so ridiculous in a while. If your bows are breaking, it's not from the string being "overbuilt." Yes, the string needs to match the bow, and a 14-18 strand B50 string will be good for just about any bow. Fastflight is excellent non-stretch string material, so is B50. If your B50 strings are stretching that much, I believe it is probably the fault of the string maker. I have not had any problems with B50. It's excellent, also, and makes suitable strings for ANY bow.
Seems to me that you're making mountains out of mole hills. Skinny strings are uncomfortable to shoot. Period. The skinnier the string, the more it WILL stretch.
ADB,
I post here to discuss things I am interested in and give a genuine opinion. Isn't that what this site is for? To be frank I find the tone of your response somewhat insulting. I don't want this to be a personal thing so please don't make it one. I don't really care if you disagree, but why not disagree in a more friendly way?
In my opinion (and I am entitled to have one) a too strong string can risk damaging a bow. I am happy to change that opinion as I learn more or as new facts come to light.
I think of it this way. A too strong linen backing can cuase fretting or chrysal damage to the bow belly if it doesn't stretch to suit it. Isn't a similar effect possible from a too strong string that is not designed to suit the bow?
Please note that "my" bows are not breaking. I reported that many bowyers here in the UK would not in the past advise using fastflight string, or expressly excluded thenm from any warrantee for fear of breaking the bow. This has been shown to be an unwarranted fear. Modern bow string materials can and do work well on longbows, if they are built appropriately.
Yes, there are many excellent string materials. I haven't built strings out of Fastflight though I have used Fastflight strings that others have made. They worked fine on longbows. I have used, BCY450 and 450plus in strings I have made. They worked fine. I don't contest that.
Dacron does stretch. A string made in a material like 450plus must be made an inch or two longer than a dacron string to end up with the same brace height. A dacron string whether 8 strands or 16 strand will stetch when first put on the bow until it reaches an equalibrium that means it is "worked in". I have seen this on commercial double loop 16 strand strings and on similar 16 strand duoble loop strings I have made and on 16 strand flemish twist strings I have made. even once worked in to it's final length it will stretch a suprising amount on the bow. If a bow has two worked in stringsone in dacron and one in 450plus, even if both give the same brace height the Dacron string will be quite a lot shorter (because of the inherent stretch)
This is an basic and well known property of Dacron. To suggest that Dacron stretches because of a fault in the string maker is not really well argued in terms of fact. Dacron can make a fine string fr any bow. I personally don't much like it, but I am free to have that preference while respecting yours.
The skinnier the string the more it will stretch? Why? Stretch is not due to the cross section or skinnyness of the string alone. The stretchier the string material and string construction and the weaker the string is compaired to the force exerted upon it the more it will stretch.
I entriely agree that it would be foolish to risk a bow due to poor string choice. A string is much easier to replace than a bow.
Anyway, as I didn't relly post here for a personal arguament I won't get any further into one.
Best wishes and happy shooting,
Mark in England