There are more bikes than people in the Netherlands. The country’s 16,8 million inhabitants own over 18 million bikes. But less than 10% of cycling trips are just for fun and leisure. The bicycles are actually used as transportation within cities to go to work, go shopping or meet friends. This is great for the environment and for health, but minerals and metals are needed to produce bikes. Where frames used to be mainly made of steel, more bikes have aluminium or even carbon bike frames these days, because these materials are much lighter. Even the rubber tyres contain numerous minerals, like zinc, sulphur, salt, iodine and silica.