Out here about 95% of all riders initiate or wave back. This topic has indeed been discussed at varying lengths in the past (e.g.
When did everyone become a butthole?), but this is a (near) definitive list of reasons why some of them don't wave.
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 acknowledgement.
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.
Top Ten Reasons Why Dual Purpose Riders Don't Wave Back
10. Off road elbow guards, chest protector, fanny pack, drink system binds them up.
9. Bark busters and gummy grips slows the hand from raising quickly.
7. Just can't take time out from doing that 10 mile wheelie through traffic.
9. He's passing street bikes off road on the right @ 60mph through the trees & rocks.
6. Too busy checking his enduro roll chart doing mental time/mile math so he wont blow the next check point.
5. Can't see other bikers through his 20 layers of tear off's.
4. The dude only recognizes Honda's with every after market race part known to man.
3. His killer 2 inch tall knobies vibrate so bad vision is obscured.
2. The chin guard on his full face helmet sticks out so much it blocks his view.
1. He's got his Mauna Kea 200 race face on and can't be bothered.
Top Ten Reasons Why Moped & Rukcus Riders Don't Wave Back
10. Scared ****less to remove a hand from the bar's.
9.Never road this fast on a two wheel anything before.
8. Full focus three inches from front tire.
7. Freeked out on the extreme right side of the road dogging broken beer bottles and car accident trash.
6. Don't want to lose their grocery's in plastic bags hanging from the bar's.
5. Won't deter from the full attention military riding position.
4. Their mother & grandmother told them it was very, very dangerous.
3. Think it's hoodlum stunt riding.
2. Don't want to chance getting a reckless driving ticket.
1. 25 mph is too damn fast to try something stupid like that.
