Let's take 'Barebow' as shooting without a sight and a longrod and V bars.
The metal sports ILF risers produced by Hoyt, W&W, Samick and others are intended to be used with a full olympic set up - the aforementioned sights and stabilisers.
They are intended to balance vertically and horizontally 'fully clothed'.
Take one of these risers and shoot it 'naked' and the top limb will kick back at you. You'll also find it quite light and skittish during aiming.
Put some weight on the lower riser and now it's easier to aim and can jump forward vertical on the release. This is the reaction that most people like.
This is the new Spigarelli BB (B.are B.ow) riser; looks related to the 650 Club. Note the after-shot reaction.
http://www.youtube.com/watch?v=fUH-rn8ivm0
The BB-specific risers are designed to be dual purpose, olympic recurve and BB, but make heavy OR risers. They come with weight kits to balance them for BB.
These are integral, often shoved into holes in the lower riser.
These are Best Moon risers.
These are Bernardini risers, the three on the right are target risers. From right to left, Lxor 27", Nilo 25", Nilo 23". The other two are a Cobra 21" riser and a Mamba 19" riser.
The holes in the target risers are for the addition of weights .
You can also come at a BB riser from the other side, the adapted OR risers. For a company with a derisory attitude to BB a lot of Hoyt risers will make decent BB risers.
The Gold Medalist, Elan, Matrix, Nexus and recently the FRX have been campaigned successfully.
Andrew Rees, GB field archery team, shooting an Elan, with a brass weight.
But note the aftershot reaction:
It's personal preference but I'd like more weight down low.
At any BB competition you'll see any of the OR risers adapted to BB by using screw in weights.
Sergio Cassiani, Italy with a W&W Exfeel and in the backround Bobby Larsson, Sweden, with a Spigarelli 2001 VBS (BB riser).
Zane Smith, US, with a W&W NXpert and Guiseppe Seimandi, Italy, with a Greenhorn Sirius (the new fad in BB risers for FITA).
The screw in weights can be locally made or bought from archery suppliers, Spigarelli do chrome weights in 190, 250 and 350 gm.