What is the normal maximum amount of negative "g" forces allowed for a roller coaster ride?

1 answer

Recent legislation limits g forces to 6 g's on roller coasters, for safety reasons. It makes no difference if it "negative" (up), down or sideways.

See http://www.iaapa.org/industry/funworld/2003/Mar03/Features/G%20Forces/G%20Forces.html

This is not an answer that can be derived using physics alone. It was established by committee and legislated.