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Main Boards => PowWow => Topic started by: M_Kanzler on September 30, 2010, 10:42:00 PM

Title: What brace height for Bear Cub 62" 27pound?
Post by: M_Kanzler on September 30, 2010, 10:42:00 PM
We got a Bear Cub recurve for my son.
It's AMO 62" and 27 lb. draw.
The string that came with it was obviously too short - it was only 57" and the brace height was almost 12".
So I bought a 58" long string from 3Rivers, which got the brace height to about 9", which still looks very high to my eye.
What would the correct brace height be?
What would be the consequences of too high of a brace height (I expect it to settle in at around 8-1/2" once the string stretches).

I am a little worried about over stressing the bow because it has some long cracks in the fiberglass on the front (belly) of the bow. Since the front is under compression, it is probably not as bad as if the cracks were on the back of the bow (the backing is under tension).

I have the bow strung right now, but will probably suspend a weight from the string to stretch it. The string is for bows up to 40# (14 strand). My research shows that a string usually has max tension in it when the bow is not drawn, and that is about 1.2 times the draw weight of the bow (string tension goes down as you draw, then goes back up near full draw). I figure I can safely hang 70 pounds overnight to pre stretch the string (I'd imagine with safety factors mfrs use the string would be safe to well over 100 pounds).
If that doesn't get the brace height looking better I will have to order him another string (ugh). The reason I went with 3Rivers instead of a custom string was to get it fast, and to keep cost down (My son doesn't need an expensive string).
So, whatdya think?
Title: Re: What brace height for Bear Cub 62" 27pound?
Post by: M_Kanzler on September 30, 2010, 10:47:00 PM
I just found this:
 
QuoteDacron B50 - strength per strand = 22.5 kg. & stretch = 2.6%
That would be 694.5 pounds for a 14 strand string!
Title: Re: What brace height for Bear Cub 62" 27pound?
Post by: M_Kanzler on October 01, 2010, 01:30:00 PM
http://new.wavlist.com/soundfx/014/cricket-1.wav
Title: Re: What brace height for Bear Cub 62" 27pound?
Post by: eagle24 on October 01, 2010, 01:42:00 PM
8 to 8-1/2" is where I shot the older Bear recurves I've owned.  I'd shoot it with that string and see how it stretches and how it shoots.  I think you are probably fine with the stress cracks you describe.  I've seen them on many older Bear recurves.  Get an opinion from someone else though.
Title: Re: What brace height for Bear Cub 62" 27pound?
Post by: M_Kanzler on October 01, 2010, 05:05:00 PM
Thanks!
I see you are in North Alabama...
We lived in Trinity & I worked at MSFC about 10 yrs ago.
Title: Re: What brace height for Bear Cub 62" 27pound?
Post by: eagle24 on October 01, 2010, 05:17:00 PM
QuoteOriginally posted by M_Kanzler:
Thanks!
I see you are in North Alabama...
We lived in Trinity & I worked at MSFC about 10 yrs ago.
Wow! You made a hefty move across the country.  I lived in Huntsville when I was a kid.  Now live in Albertville.
Title: Re: What brace height for Bear Cub 62" 27pound?
Post by: Warberg on October 01, 2010, 05:18:00 PM
well, I have a 62" in o# 15# 20# 25# 48#.  all seem to shoot best for 7 3/4 to 8 . great bow and my all my kids prefer the Bear cub model. great bow. best wishes.
Title: Re: What brace height for Bear Cub 62" 27pound?
Post by: mahantango on October 01, 2010, 05:51:00 PM
They are a great, underated bow. Mine shoots best at about 7 3/4"- 7 7/8".
Title: Re: What brace height for Bear Cub 62" 27pound?
Post by: M_Kanzler on October 01, 2010, 11:07:00 PM
Thanks.
I'll have to use what we have for now - I hung 80 lbs on it for about 24 hours to pre stretch it...
it looks like the string is about an inch longer now. Haven't strung it to check yet (spent the day on the roof of my "Laboratory")

I have a fire hydrant from Albertville.
Found it when we lived in So. Calif...
Had no idea I would ever live in Alabama...
moved it all the way to Huntsville, then
to Seattle. It weighs about 250 pounds!