The main reason for added mass at the handle/riser, and stabilizers, in more modern designs (think modern recurves, esp on an Olympic target line) is to absorb shock as well as stabilize aiming.
i have to disagree with this statement Paul. The mass of the riser definitely helps stability, and the stabilizers are for balance in the hand. It has nothing to do with absorbing shock.
The limbs on an OLY rig are timed to perfection and there would be no hand shock....even if the riser was lighter weight there would be no hand shock.
Getting back to s/f bows.... Nate nailed the description to a tee but left out the part about string tension at brace, or preload.
besides limb timing, which is a critical part of getting a shock free bow. the string needs enough tension at brace to stop the forward motion of the limbs and transfer that stored energy to the arrow shaft.this is critical when shooting lighter weight bows with lighter weight shafts.
if you are measuring the arrows performance by using a chronograph, a reflexed limb with a higher preload (more string tension)will most always be faster if they are balanced correctly.
A straight bow with long limbs and a short handle, as well as most string follow bows, (Not all) has more mass in the limbs coming forward, and typically not enough preload at a 6-6,5" brace to stop the forward momentum of the limb.That's where the hand shock, or that "Hill thump" comes from, even on a perfectly timed limb.
Now this is the interesting part.... The efficiency of the bow itself on a s/f bow, or a straight bow will rise with heavier arrows, and seriously decline with lighter weight shafts....
i'm not talking feet per second on the arrow, I'm talking about the percentage of stored energy in the limbs being transferred to the shaft instead of staying in the limb and flopping around.
These bows are naturally going to shoot a slower arrow, but have the ability to shoot much heavier shafts which transfers more of the stored energy to the arrow and leaves less hand shock.
ok.... Where all this changes is when you start talking about string follow bows and hill style bows where the poundage is up to 60-70 pounds at 28". the string tension at a low brace is much higher and stops the forward motion of the limb mass cleaner.....
There are ways to accomplish this with glass and carbon backed SF and straight limbed bows of lighter poundage to increase performance and eliminate hand shock..... but i wont go into it.
bottom line is trhat all bows are not created equally, regardless of design categories.
Great thread here guys!