Sinew backing

[MXer]

I want to know if sinew backing increases the poundage of pull or just simply provides a way to keep the wood intact.  I have only used rawhide to back a juniper bow.

[hartj57]

If I understand correctly, sinew does tend to increase your poundage, but only because it shrinks as it dries, pulling the bow into a reflexed shape.

[Cade]

Yes, from what I have read on here ( I just got some deer sinew last weekend and haven't tried it yet.) depending on how many courses you use it could up the poundage by 5-10 lbs.

[bowandarrow473]

If you add sinew, the poundage will most definitely increase.

[sleek]

Recently had a 45# bow done with sinew. 45# when started, 4" reflex induced, it was 75# when cured. Had to retiller it. Two courses of sinew.

[LittleBen]

There's definately no formula for how much weight sinew will add. My experience is the more you add the more the weight goes up .... Captain obvious .... I know.

You can get ridiculous increases in draw weight with sinew as mentioned.

[Pat B]

...but also, sinew/hide glue weigh more than wood so just because the draw weight goes up doesn't necessarily mean the bow's performance will be any better. The extra physical weight can reduce performance.
I've heard sinew backed juniper makes a fantastic combo.

[bownarra]

Actually sinew doesn't add anywhere near as much weight as a comparable thickness wooden backing would do.
However to answer the question yes it will raise your draw weight.
The factors to consider are its density when cured is about 1.3 s.g. and it has low stretch resistance compare to wood. Both of these basically mean you should use it on a short, strained to the limit wooden bows.
As a means of increasing draw weight on a finished bow - not the best idea as yes you will increase the draw weight yet certainly DECREASE its efficiency which = slower arrows for a lot of work  
I always say the best way to increase weight is to ..........start again and work slower!

[PatM]

As long as your bow is strained to the limit , it doesn't have to be short. Sinew allows a bow to be repeatedly strained up to those  limits better than just a wood or bamboo backing.
 Those constantly repeated mantras of it adding weight and decreasing efficiency are a product of poor design, not the material property itself.

[BowEd]

Diddo to what Pat M said.

[BowEd]

If you want to use sinew or horn on a design of a bow MAKE IT DO IT's WORK that it can do for whatever reason.Sinew stretches farther and horn compresses more than wood by far.Then if you like tillering a bow with lots of reflex you'll like the results.

[bradsmith2010]

what Pat said
also here is an example of how adding sinew can increase bow weight,,
lets say you miss your weight on a self bow,, you are at 30# at 28 inches,,, your bow is 64 inches long,,shooting close to 130 fps with a 500 grain arrow,,
now you think positive
ok cut the bow to 56 inches for a 28 inch draw and gently heat it into some reflex,,
now sinew back it,,800 grains of sinew

let it cure and now you can barley string it,, you get it tillered to 55# at 28 inches,, since the stave had been shot in,, it is not a rocket launcher,, but it is shooting the 500 grain arrow at 160fps maybe 165fps,,,,, slow for a sinew bow,, but alot faster than the 30# was shooting
and well worth the effort if you cant afford to buy another stave to start a new bow,,
you have a great hunting bow that will last your life time,,..well worth the effort,,