A long ago clubmate of mine would disagree. She was launched headfirst through the passenger side window of a car that abruptly turned left in front of her. Her helmet was demolished, but her only injury was a dislocated shoulder. She brought the remains of the helmet to the next club meeting to show us.

Every single place that mandated helmets (or heavily promoted) saw absolutely no reduction in death/injury.

There are too many variables to go over every country (i.e. mandated only for kids and teens). And even when they are mandated, compliance may still be low (B.C, Canada has helmet laws for all ages, yet compliance is <70%).

That said, every study I've seen, including meta-data analysis, shows benefit.

For instance THIS very recent study:

"The empirical evidence based on the real-world hospital and police data as well as biomechanical studies confirms that wearing a helmet while cycling is beneficial, regardless of age and crash severity, in collisions with others or not. The relative benefit is higher in high-risk situations and when cycling on shared roads. The findings from the meta-analyses studies that have been reviewed in this paper are remarkably consistent."

The classic example is Australia – it had almost no helmet usage prior to passing a nationwide law. The law was strictly enforced with extremely high fines, and yet there was no real change comparing before/after the law.

Wait, what? This Australia?

Quoting Professor Jake Olivier of UNSW’s School of Mathematics and Statistics and Deputy Director of the Transport and Road Safety (TARS) Research Centre:

"There was an immediate 46 per cent reduction in the rate of cycling fatalities per 100,000 population following the introduction of bicycle helmet legislation in Australia,” he says.

“This decline has been maintained since 1990 and we estimate 1332 fewer cycling fatalities associated with the introduction of bicycle helmet legislation to date.”

And you also have to consider that non-injuries (i.e. walking away from a fall because of your helmet) won't be reported, so the benefit may very well be significantly higher.

All I can say is that I'd rather be wearing a helmet than not, in the event that my head hits any object, at any speed. It's such a "set and forget" piece of gear, and I know people who have walked away from crashes (not involving cars, just crashes due to poor surfaces) yet their helmets basically crumbled upon impact. Way better than the alternative.

But you do you. I don't want to force anyone to do something they don't automatically see as a benefit on the bike.

As one study put it, "Unhelmeted injured cyclists were frequent commuter cyclists who generally do not regard cycling as safe yet choose not to wear helmets for reasons largely related to convenience and comfort. " 🤷‍♂️