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RACING cyclists often ride in packs so they can reduce wind drag. But some
say that this gives poorer cyclists an unfair advantage, as they can tag along
behind the leaders. Now Graeme Ackland and David Butler of the University of
Edinburgh have put together a mathematical model that describes how this
clumping happens. Cyclists speed up whenever they see someone ahead, but the
researchers found a surprising critical threshold: clumping only happens when
more than 13 per cent of competitors can catch up with leaders. That can be
prevented just by staggering the start times of the cyclists. But some cycling
authorities might not take the advice, says Ackland, since the pack riding
together 鈥渓ooks great on TV鈥� (Nature, vol 413, p 127).