Nothing is required, except insurance (by law). The rest is really for us - we're selfish. When we're riding with you, I don't want to come into a turn hot only to find out you've stained it with blood and caused me to wreck too. Pants are just a good idea, but unless I'm on a trackday I usually am geared up with everything BUT pants - so I'm going to be a hypocrite and not practice what I preach.