Speculation please

[Badger]

The biggest thing for high string tension is Lowe's string angles that brace, so the longer your low string angle the higher that brace tension

[Deerhunter21]

In the TBB 1 it has graphs just like that in the bow design and preformance. bet you could find it there.

[DC]

Is that supposed to be "low string angles at brace" not "Lowes string angles that brace"? I did a google search and got garden tools Glasses still missing

[DC]

In the TBB 1 it has graphs just like that in the bow design and preformance. bet you could find it there.

I've read that chapter at least 10 times

[Badger]

I just started using a cell phone

[sleek]

I just started using a cell phone

You will love it and you will hate it. It wants to make typos for you, but it's nice to have all the information access in your pocket.

[DC]

The top one has 96# of string tension and the bottom has 76#. Are you seeing a lower string angle on one? Sorry for the fuzzy pic.

PS I thought I would put another unbraced pic where we could see them together.

[leonwood]

Now this is just a guess but I would think the amount of reflex before the recurve makes for extra high braced tension.
I drew some lines on your pics to show you the top bow has a lot more of "pre-recurve" reflex. I know on the bows I did this with compared to just deflex and recurves it makes a lot of difference.

[Badger]

I do see a lower string angle on the top one. It also matters how long the low angle is. You can see the dip in the Upper Limb even when braced. This would account for the extra tension.

[DC]

Now this is just a guess but I would think the amount of reflex before the recurve makes for extra high braced tension.
I drew some lines on your pics to show you the top bow has a lot more of "pre-recurve" reflex. I know on the bows I did this with compared to just deflex and recurves it makes a lot of difference.

I do see a lower string angle on the top one. It also matters how long the low angle is. You can see the dip in the Upper Limb even when braced. This would account for the extra tension.

You are both commenting on what I was thinking, I think. When I was tillering this bow on the long string when I got to about brace height that bend would kinda "pop through". Kind of an "oil can". I wondered at the time if that was a good thing. I'm thinking the high string tension is part of the "popping". Do we know if that is a good thing? It might give the arrow a last minute shove. Shouldn't we see some remnant of this on the FDC?

[Woodely]

That was easy, a length of chain and a turnbuckle makes it infinitely adjustable.
OK this is interesting. The 50# bow has 76# of string tension. The 40# bow has 96#. Now if I could just figure out why. I made the test "string" the same length as the bows normal string. Brace heights are with an eighth inch of each other.

I don't quite get this string tension stuff,  how could a lower weight bow have more tension..?  And how are you measuring the weight, ?  with the luggage scale..? Got any photos of this weight testing.

[DC]

The scale is basically inserted in the string. I'll take a picture in a bit. I read fairly early on that string tension was higher than bow weight and I measured it on some of my first bows. It was a few pounds higher but nothing dramatic. It was when I measured this bow that I found that my luggage scales couldn't hack it. I had to use my 300 lb scale. 

  how could a lower weight bow have more tension..?

Haven't quite figured that out yet but I believe it's the mechanical advantage that the string has that raises it above draw weight. I have to do more testing but I think changing the brace height will change the string tension quite a bit. I have to make a jig that I can adjust under tension to check that. I do know that the string tension drops as you draw the bow. At full draw string tension and draw weight are the same or at least close to the same.

[bradsmith2010]

so would raising the brace,, lower the tension,

[Badger]

 I am pretty sure a higher brace height would lower the tension

[DC]

Strange, there seems to be a sweet spot. My string tension jig has a chain with 5/8" links so I raised and lowered the brace height by one link. So normal BH was 97-98#, shorter string(higher BH) was 88#, longer string(lower BH) 92#. I did it twice because I didn't believe it. Now I have to make an adjustable one so I can crank it up and down while I'm watching it. here's some pictures of the jig.