Seriously though.

New riders I haven't been introduced to warrant a nod of the head. 

New riders being introduced to, standard handshake.

2nd, 3rd or 4th time after a couple rides and or drinks at the pub, handshake around the thumbs. You'll know.

Good riding buddies and friends, same handshake with an optional quick lean in and pat on the back.

If seated on the bike and saying hello or farewell after a ride, knock clenched gloved fists together.

I don't wear a patched jacket of any description. That's just me. Wear a SOA jacket or shirt at your own peril. You need to have earned the badges or moniker. 

Haha, there are some really funny comments posted back and forth. Keep them coming fellas.