The Bonk, Hitting the wall each sport has it's own name for it. It's when you blood sugar levels drops and you run out of energy. Your body usually has enough stored energy to last two hours before it hits. The first signs of the Bonk it you actually start to feel stronger you pace usually increases, then you'll find that you start sweeting then it hits. It's like have a puncture in both legs. Every cyclist has had the bonk at some yime.
JODRELL BANK CYCLOSPORTIVE 2011