You see the clouds in the sky? They are made of tiny water droplets. At some point the cloud is saturated and the droplets get too big to stay suspended in the air any longer, so they start falling towards the earth as raindrops. Some may hit a cyclist and either roll off their raincoat or get absorbed by other clothing until they evaporate again, travelling upwards into the clouds and starting their journey all over again.
The cycling revolution in Paris continues: Bicycle use now exceeds car use ( english.elpais.com ) Englisch