^^ They were probably so surprised at seeing another Spyder that they just froze up!! :yikes:
Didja pop a U'ee & chase them down?? :shocked:
I often find that Spyders we've just passed going the other way hesitate & sorta look around/wait to see what you are doing before continuing on their way at their previous speed (unless they are going somewhere in a hurry or they have a pressing need elsewhere of course) & a quick (but safe) 'U' turn will often catch them just a coupla hundred metres up the road where a quick exchange of info can lead to lasting friendships. Met lots of 'new' (to me) Spyder Ryders that way, they are usually so surprised at seeing another Spyder that they just didn't get a chance to respond to the wave from me - of course, that could also have something to do with how fast I was travelling too!

pps:
As for waving in general, I just wave at whatever in the most convenient way at the time. No real 'pattern' or specific technique; sometimes it's just lifting a couple of fingers on the nearest hand, other times it's a full on 'whole hand off the handle bars' thing & a full on wave; & I have been known to use just about every waving technique or method in between!
AND I wave to 2wheelers of all sorts, Harley Riders (wannabee's or 'real', duz'nmatta!) Sports Bikes, Cruisers, Trikes, Scooters, & even the odd quad - and since I've been fairly heavily involved in the transport world in a variety of ways over many years now & most 'regular road users' out there (locally at least) know me & what I ryde these days, I often wave or get waved to by Police, Ambo's, Firie's, Truckers, 4Wheelers, Taxi Drivers, farmers on their tractors, & car or truck fanatics of all types!!
I don't really think
HOW you wave matters all that much, nor really
WHO you wave to; just the fact that you
DO wave; simply that you are out there enjoying yourself & greeting other road users is what it's all about - and there's no score sheet either, so who cares if they don't wave back, altho I do try to always acknowledge a polite wave directed my way from other road users!! Just between you'n me, I have a different way of 'acknowledging' the 'not polite' waves, but let's not go into that here!
