Yeah, and I’m definitely bordering on talking out my @$$ here, but my understanding is that as with so many things, there are trade-offs with any bow design, and short bows are no exception. Obviously, by its very nature, a short bow will have short working limbs. Short limbs may have other advantages, like maneuverability in the woods, but high performance isn’t one of them, without also adding significant pre-load (D/R). The limbs are the spring – the shorter the range of the spring, the less ‘bounce’ you’re going to get. And so a short bow, with straight, short limbs, is by nature not going to have much of a ‘power stroke,’ making it pretty anemic.
This is also one of the reasons you will tend to see quite short risers on short bows – to maximize the length of the working limbs.
With all that said, a higher vs. lower brace height, and any resulting changes in performance, are really only relative to that particular bow. A 68″ D-shaped longbow may have a “low” brace height of 6-1/2″ while a “low” brace height on a 54″ Thunderchild might be 7-5/8.” Both are still at the “low” end of their particular brace height range, which will typically result in more power, but all things have their limits – if you put the low brace height of the Hill bow on the Thunderchild, you’re not increasing performance at that point.
So yes, a deflexed riser increases brace height on a short bow, in tandem with other design elements, but there can still be an “ideal” lower brace higher height which gives more power for that design.
I might be talking in circles at this point, but I hope that makes some sense?
