I nod at most, most of the time, not at cruiser riders unless they nod first, but i've been supprised at the lack of nodding these days, I think Katooom is right biking has suddenly got all trendy and the real diehard bikers from the old days are fewer it seems.   The worst thing of all is it's getting harder for young people to get on a bike these days so will i wonder biking die out once us old cronnies have given it up for our bath chairs...                                                                                                                                                                              

Yes...always!
Everyone used to nod 20 years ago, but no where near as many people nod now???
I must be getting old! lol!
                                                                                                                                                                             

 I don't think the great wonder of biking will ever die easy.
I started in the early 1960's when there were a large number of bikes around. I include the old mods although I was of the fraternity. But half my mates were mods the other half pure bikers. OK I was confused!
In the early 1970's there was a noticeable lull in the numbers of bikes. Younger people were getting into the car scene. But by the 1980's the popularity came back and seems to have increased since then. I have given up biking 3 times; I thought that’s it no more, too old. Well at 62 I got myself another bike and here we go again. Once in the blood it is always there.
As for nodding I limit the number to acknowledgement for giving way etc. I don't remember nodding in the early days. Rockers would probably take a nod the wrong way. The nearest to a nod that you may have got was another forehead approaching yours rapidly before you sensed immense pain.