Contributors to this thread:
Weight Difference ?
The difference between bow draw weight is created how? Is it the stiffness of the limbs (stiffer limbs for a 60-70 than a 50-60), the angle of the limbs, the pre-stress created by different rigging and cam, etc? I m assuming it is actually the limb where the variance is created
An observation over the years the limbs have become shorter and shorter and they have migrated from a vertical orientation to a more horizontal orientation .
In my view they don’t even seem to be the major component of most compounds these days just a device to hold the cam . It would be interesting to see high speed video footage comparing the actual amount of limb movement from the longer vertical style limbs to the the more recent adaptation of the short horizontal limb orientation.
Such a dramatic transformation of the bows outline over the last 70 years .
I think cams have a ton to do with it I just bought a new now and it’s the same weight as my last bow but pulls significantly easier. I was convinced the draw was turned down it was so drastic.
Regardless of orientation, the limbs are still what stores the energy for the shot. The advent of parallel limbs was primarily to reduce hand shock. Instead of both limbs moving forward, parallel limbs move away from each other, thereby canceling out the vibration felt in the riser.
The limbs at least on older bows iv bought a different # set of limbs & switched cams cables & string no problem perhaps the newer horizontal limb large cam bows are different not sure
Grey Ghost is correct; one other thing about parallel/beyond parallel limbs is that moving in opposite directions takes the “slack” out of the string at the fastest possible rate.
But cam design certainly figures in as well; they can give you more leverage against the stiffness of the limb or less (which is how let-off is achieved), but unless you’re talking about “youth” design with a #50 adjustment range, the only difference between a #30-#40 version of a given bow and a #70-#80 is the limbs, isn’t it?
I guess you could screw around with altering the lengths of cables and what not, but I’m pretty sure that you’d screw up the timing and alter the draw cycle in the process. Not such a big deal on a Youth model, but if anyone out there is offering a high-performance model that adjusts over >#10, that’s news to me....
But I guess that’s what happens to you when none of your bows are adjustable beyond twisting your brace height up or down a few 1/16ths of an inch....
It most is limb deflection however can alos change the limb angle in relation to the bows power stroke, or how the cam tracks. Thats the reason matthews can use one defection of limbs and differnet draw weight mods to achieve different peak weights.
So to make this easier to describe if you wanted to change a bow from 40-50 to 90-100 what different parts would You have to order to enjoy that weight gain
PS. the answer a new rotator cuff does not count.
For a given model of compound bow, where cam design and overall bow geometry are equal, the high draw weight models need thicker limbs.
Draw weight = limbs
Felt weight = cams