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.
Why Isn’t There Consensus? Unpacking the Opposition to Helmet Laws
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
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
OpEd: The Unintended Consequences Of Bicycle Helmets
via @cardiobrief https://www.medpagetoday.com/cardiology/cardiobrief/65801