Damn. That would be a problem.
One solution: Cycle traffic counts could be carried out and signs posted indicating whether the levels of cycle traffic were sufficiently high that nodding or waving would only be required between cyclists of a similar, easily identifiable, sub-type. That way most people would get a nod (tall bike riders, velomobilists etc. might miss out). Some sort of cycling thug army would be required to dish out beatings to ensure compliance, although that's just my solution- less evil types could perhaps think of a nicer way to go about it.