AMO bow/string length

[Bladepeek]

From what I've read, a recurve bow usually requires a string 2" less than the length and a longbow, 3" less. I have several recurves and a few more longbows. Not a single one of them comes close to that. I'm guessing the lower brace height of most longbows from an 8" standard might account for this. I called the bowyer and asked him the string length for his 62" r/d longbow. He supplies FF strings with his bows and he told me 59". I ordered a good 59" SBD string (which will be for sale in the classifieds) and got an 8" brace height. The bowyer recommended a 6 3/4" brace for this bow. I have seen very few custom bows with the string length marked on them. Why not?

[WJackson11x]

A recurve string is typically 4" shorter than AMO.  Obviously you would want to measure your existing string is possible.

[JamesKerr]

I agree for a recurve you usually want a string 4" shorter than the bows AMO length. You would do best with a 3" shorter string on longbows. I follow this rule pretty closely when making my own strings (flemish twist) and have always been pretty close to where I need them.

[Pete W]

AMO bow string length is 3" shorter for both recurves and longbows. The problem is bowyers don't always label the bow length properly .
   AMO Standards

[elknutz]

I have two 66" longbows.  Both bows brace properly, about 6 3/4", with the strings at 64".

[Bladepeek]

OK, I guess I have bows that aren't labeled properly, but the ones labeled 60" take strings about 58 1/2 and of the two labeled 62", one takes a 60.5" string and the other a 60.25". With the skinny FF strings it's hard to get a lot of adjustment by twisting. It just seems like a custom bow costing upwards of $600 should carry a marking that would give the recommended brace height for that particular bow. Then it could be tweaked up or down from there as necessary. Yeah, I know. Quitchurbitchin and be glad you have a nice bow.

[SlowBowinMO]

Originally posted by Pete W:
AMO bow string length is 3" shorter for both recurves and longbows. The problem is bowyers don't always label the bow length properly .
   AMO Standards  

+1.

If the bow is truly 62" AMO, that is supposed to mean it braces properly with a 59" string.  AMO length is supposed to be -3" for proper brace as specified by the bowyer.

As you've seen many trad bows don't match this, we find this especially common in longbows, so it is important to know the actual string length for your bows.

The old 4" less for recurves comes from the days of B50, which stretches a lot, and the fact recurves typically brace higher than longbows.  In a modern material, pre-stretched string -3" for recurves is usually correct, although Black Widows typically need a slightly shorter string than most recurves due to their higher braces.

[Night Wing]

I own two 66" Blacktail TD recurves. When I ordered my first 66" Blacktail, I asked Norm Johnson what length string is used on these length bows. He told me for my 66" take down recurves, they take 62" bowstrings.

[Lechwe]

My widows and Robertson have all needed the standard -3" string.

[Swamp Yankee]

You can save yourself a lot of time by ignoring the AMO "Standards".  Most bowyers simply do not comply with it.  I don't know why because it certainly would save us all a lot of time and money if they would.
IMHO, the best solution is either use the old string length if it's available, or an adjustable tillering string to find the string length needed to get to your desired brace height.  Forget about any standard math formula, they simply do not work for all, if not most, bows.

[LBR]

I agree with a lot of what's already been said.

The AMO bow length is supposed to be 3" longer than the string that puts it at proper brace height.  As far as I can find out, it's always been 3"--with the string measured under 100# of tension.

As noted, many bowyers don't follow this rule.  I'll add a lot of archers don't either--they set the brace where they like it.

That's why I take orders by string length, not bow length.  It's also why the string board instructions in our videos show you how to label it by the string length you want to make.

Going by string length eliminates a lot of guesswork.

Chad

[JRY309]

When I make a string for my bows I like to measure the actual string length at the brace height.If I don't have a string I'll measure the actual nock to nock length of the bow and don't go by the AMO marked on the bow.I had 3 different 64" longbows and measured them,there was up to an 1" difference in the actual nock to nock length.