Sorry to all who tried that URL, and got caught up in Geocities. If you mean caster, I'm using about 4-5 degrees. I know that some recommend 12 deg, but I tried that, and it seemed a little silly. I've got no front brakes. Before this design hits the sellable stage, I plan to turn my own fron hubs and axels, and make an integrated disc brake for longevity.
Caster is the angle as seen from the side.
The reason for the 12 degrees is so a line through the turning axis hits the ground directly in front of the tyre contact patch, and not inboard of it.