Wearing a helmet when cycling can be beneficial in specific incident scenarios, but the evidence suggests that making wearing them mandatory - i.e.: the law, not the performance of a helmet in a crash - has a net detrimental effect on overall cycling safety.
In the '80s, We Decided Bike Helmets Make Riders Safe. Cyclists Have Paid for It Ever Since.
https://slate.com/technology/2023/01/bike-helmets-cyclist-deaths-do-you-need-to-wear.html
"People should wear helmets when cycling"
via @CyclingFallacy https://cyclingfallacies.com/en/29/people-should-wear-helmets-when-cycling
Debunking the Biggest Myths of Mandatory Bicycle Helmet Law Advocates
via: @warriorfactor https://warriorfactor.wordpress.com/2018/10/13/debunking-the-biggest-myths-of-mandatory-bicycle-helmet-law-advocates/
if you don't like wearing a bike helmet, you might like to read this...
via @sarahwilson http://www.sarahwilson.com/2010/12/if-you-dont-like-wearing-a-bike-helmet-you-might-like-to-read-this/
The effects of New Zealand's cycle helmet law: The evidence and what it means.
via @CHAIRRDRF https://rdrf.org.uk/2013/12/27/the-effects-of-new-zealands-cycle-helmet-law-the-evidence-and-what-it-means/
Motorists Punish Helmet-Wearing Cyclists With Close Passes, Confirms Data Recrunch
via @carltonreid https://www.forbes.com/sites/carltonreid/2018/11/14/motorists-punish-helmet-wearing-cyclists-with-close-passes-confirms-data-recrunch/#1e5872e54859