Maybe it's a NY thing but there is no waving between species.

 

I signal two fingers to most sportbike, likely they will wave back first....Harleys, I just nod....I reserve my 1 fingers for those that want it...or deserve it.

 

New rider here, so keep that in mind with my post
On the two rides I went on this week, everybody I passed waved and I waved back, IF I felt comfortable doing so. Going through corners, I didn't wave because I didn't feel comfortable taking a hand off the bar. Also, it didn't matter what they were riding. Harley, sport touring, etc.... Maybe it's a "Montana Thing", I don't know.....

 

Living in an area where there are a lot of riders, its common to drop a hand or nod. Unless the other rider is a 'club' type, they almost always acknowledge.

Also, the courtesy or a tap or five on top of the helmet to warn of upcoming 'hazards' is routine in the area as well.

 

I try to wave at everybody that waves at me, unless I don't see them.
I even wave at scooters, bicycles, kids on skateboards.
Most of them wave first anyway.

Good thing you bring that up Gotcbr,
I was always wondering what would be a good way to warn other riders.
I like the 5 on top of the helmet. Should grab some attention.

 

I always wave, possibly excepting clutching when pulling away from an intersection or something. Nod of the head has to suffice then. In this area, most everybody on most every pure-street bike waves. 'Adventure' bikes often don't, and cruisers are the most likely to not of the street bikes. The Goldwing/touring guys around here usually do. Even the motor officers will normally wave around here.

 

Quick and easy answer.
It is a courtesy. Someone says hi to you, you say hi back.
It's just that simple.

If you can't say hi while taking a turn, then don't.

 

I nod at all breeds of bike and scooters, unless it's a scooter being ridden by a young lad wearing a t-shirt, jogging bottoms and no gloves or something equally silly. I'll try to wave back if waved at, but the nod seems like the safer alternative!

 

It's mostly nods here and not straight up and down nods but those funny flicks of the head you'd do if you were winking at someone. I nod at all riders and about 90% nod back, I've only ever been waved at twice but I felt great when it happened but was too confused to get my hand up so nodded back instead.