Cycling in the Netherlands is extremely convenient and safe, and the architect of this goodness, the Fietsersbond, happens to be vehemently against cycling helmets and the promotion thereoff. So we're not talking about some neurosurgeon who heard some regurgitated nonsense about the magical properties of polystyrene, we're talking about world class experts in cycling safety who really know what they're talking about:

Helmets make cycling less safe, says Dutch cycling union - DutchNews.nl