Because several family members and I have experienced head injuries riding bicycles, none of us have been shot at or attacked with a knife. That said, I'm down for making all private gun possession illegal.
There's like 27000 bicycle head injuries in the US.
I'm surprised you haven't googled it.
Here's the head injury source. You can easily Google shooting and stabbings per year and add them together. https://www.nsc.org/safety-first-blog/bicycle-safety-statist...
Its pretty clear you should pick up some Kevlar and chain mail for your kids.
A natural experiment may require comparing similar communities with and with helmet laws.
Shootings and stabbings on the other had are difficult to not report. And can happen regardless of proximity to bicycles.
Ultimately let's do both: get helmets for kids and get rid of so many guns.