Waving to bikers

I know this sounds crazy in Asia as so many bikes on the road but is there a custom or culture of waving to other bikers when you meet them on the road? Here in North America and in Europe a greeting of two fingers(thumb and the index finger) pointed downwards is shown when you pass a biker going the other way. Normally this is done by bikers on cruisers.
I am sure the expats who ride in Philippines would understand what I meant.