Finally explained!!!  why not wave!!??   (best to read it in your head with letterman voice)

Top Ten Reasons Why Harley Riders Don't Wave Back

10. Afraid it will invalidate warranty
9. Leather and studs make it too heavy to raise arm
8. Refuse to wave to anyone whose bike is already paid for
7. Afraid to let go of handlebars because they might vibrate off
6. Rushing wind would blow scabs off the new tattoos
5. Angry because just took out second mortgage to pay luxury tax on new Harley
4. Just discovered the fine print in owner's manual and realized H-D is partially owned by Honda
3. Can't tell if other riders are waving or just reaching to cover their ears like everyone else
2. Remembers the last time a Harley rider waved back, he impaled his hand on spiked helmet
1. They're too tired from spending hours polishing all that chrome to lift their arms.

Top Ten Reasons Why Gold Wing Riders Riders Don't Wave Back

10. Wasn't sure whether other rider was waving or making an obscene gesture
9. Afraid might get frostbite if hand is removed from heated grip
8. Has arthritis and the past 400 miles have made it difficult to raise arm
7. Reflection from etched windshield momentarily blinded him
6. The espresso machine just finished
5. Was actually asleep when other rider waved
4. Was in a three-way conference call with stockbroker and accessories dealer
3. Was distracted by odd shaped blip on radar screen
2. Was simultaneously adjusting the air suspension, seat height, programmable CD player, seat temperature, and satellite
navigation system
1. Couldn't find the "auto wave back" button on dashboard

Top Ten Reasons Why Sportbikers Riders Riders Don't Wave Back

10. They have not been riding long enough to know they're supposed to
9. They're going too fast to have time enough to register the movement and respond
8. You weren't wearing bright enough gear
7. If they stick their arm out going that fast they'll rip it out of the socket
6. They're too occupied with trying to get rid of their chicken strips
5. They look way too cool with both hands on the bars or they don't want to unbalance themselves while standing on the tank
4. Their skin tight-Kevlar-ballistic-nylon-kangaroo-leather suits prevent any position other than fetal
3. Raising an arm allows bugs into the armholes of their tank tops
2. It's too hard to do one-handed stoppies
1. They were too busy slipping their flip-flop back on

Top Ten Reasons Why BMW Riders Riders Don't Wave Back

10. New Aerostich suit too stiff to raise arm
9. Removing a hand from the bars is considered "bad form."
8. Your bike isn't weird enough looking to justify acknowledgment.
7. Too sore from an 800-mile day on a stock "comfort" seat.
6. Too busy programming the GPS, monitoring radar, listening to iPod, XM, and talking on the cell phone.
5. He's an Iron Butt rider and you're not!
4. Wires from Gerbings is too short.
3. You're not riding the "right kind" of BMW.
2. You haven't been properly introduced.
1. Afraid it will be misinterpreted as a friendly gesture.

Letterman would be proud.....(and blame Leno for plagarism)

How come there isn't a Sport Touring top ten? Maybe we should start one....

10. Was too distracted w/ GPS,tank bag map, and arm sleeve map to know which direction to wave.

Good one 

#9 didn't see you wave, he was looking in the mirror to see if his saddlebags are still there!!

 
Nice!

 
 
Love it!! 

#8.  Too busy trying to find the right position for the adjustable windshield.