[chrstphr]

25 inch riser with short limbs will be 66 inches.
25 inch riser with medium limbs will be 68
25 inch riser with long limbs will be 70

maybe you have a 23 inch riser.

23 inch riser with shorts will be 64
23 inch riser with medium limbs will be 66
23 inch riser with long limbs will be 68


Your string should be 63 inches or a string for a 66 inch bow if your riser is 25 inches
your string should be 61 inches or a string for a 64 inch bow if riser is 23 inches


brace height can be changed by twisting string. You should have 20-40 twists in average string.

Chris

 

[Bob Furman]

Don't forget that bow lengths are measured "unstrung".

 

[Viper1]

Stephen -

Your brace height either within spec or just slightly below. If the latter, it can be adjusted by adding twists.
Since the 66" AMO string (63" actual length) gives the proper brace height, you have a 66" bow.
That btw, is how AMO measures bow length, by the string, not by the bow. Sounds counter intuitive, until you really think about it.


Bob -

Don't forget that bow lengths are measured "unstrung".

Yes, he should forget that, that's not how bows are measured, and bows don't change length by stringing.

Viper1 out.

 

[archer60x]

Thanks for the replies! And the confusion continues.... I just spent over an hour online with the tech rep and then I reread the replies here. Viper1's explanation of the way AMO measures the bow. I mean it only makes sense that if a 66" AMO string really measures 63", adding 1" for the limb tips you would end up with a 64" approx. bow length. If the string was 66" full length the bow would be 66 - 67" strung. Therefore, all is well with this newbie recurve shooter and his bow! Interestingly enough the tech rep at a large archery store (no names mentioned here) didn't really have a quick answer. After over an hour and measuring everything three times he figured the string was too short??? Even after I told him the unstrung length was 62" unstrung......what would a longer string accomplish?? Obviously he is as new to recurve as I am. Thanks guys, he and I learned something new today!

 

[Bob Furman]

Tony,

From what I recall bow length are measured unstrung from tip to tip on the back of the bow following the surface countour. Obviously the measured length will not change, but the linear length from tip to tip will. Has that changed over the years?

 

[Seattlepop]

Tony,

From what I recall bow length are measured unstrung from tip to tip on the back of the bow following the surface countour. Obviously the measured length will not change, but the linear length from tip to tip will. Has that changed over the years?

Agree. Actually, string groove to string groove, but I agree otherwise. My 68" GMX measures exactly 68" that way with 25" riser, med limbs. No other measurement gives me that.

Just knowing the string size, say a 63" string and they want to know if its the right size for their bow...how would you know? You have to have more clues...from the bow.

Talk about a conversation that made me run for the tape measure!

 

[dchan]

AMO uses the string length to determine the bow's rated length. confusing enough?

AMO CONVENTIONAL BOW LENGTH STANDARD

AMO Bow Length Standard is designated to be three inches longer than AMO Bow String Master that braces bow at proper String or Brace Height. Bow String Master will carry only the bow length designation. Example: A Bow String Master designated as AMO 66” (bow length) will have an actual length under tension of 63”. Cable length is determined by placing loops over 1/4” diameter steel pins and stretching under 100 pound load and measuring from outside of pin to outside of pin. Tolerance is +-1/16”. End loops of cable will be 1 1/4” long and plastic coated.

Bow String Master shall have the following material specifications or equivalent: 1/16” 7 x 7 galvanized (Mil-C-1511) or stainless (Mil-C-5424) steel aircraft cable of 480 lb. test.A Bow String Master Set shall consist of twenty-five Bow String Masters to measure bow lengths in one inch increments ranging from 48” to 72”; (i.e. actual string lengths 45” to 69”).

The AMO prefix to bow lengths in inches means that the bow has been manufactured to a length that properly uses a bow string designated with the identical AMO marking. (i.e. A bow marked “AMO 60”, 50 lb. will brace to the proper string height with a string marked “AMO 60”, 45 lb. to 55 lb.)