Andrey Kivilev

Andrei Kivilev (20 September 1973 -- 12 March 2003) was a professional road bicycle racer from Taldykorgan, Kazakhstan. In March 2003, he crashed during the Paris--Nice race and subsequently died of his injuries. His death was the trigger for the UCI to implement the compulsory wearing of helmets in all endorsed races.

Question: do tour de france riders have to wear helmets
Answer: yes