When my big sister was just a young girl, she crashed her bicycle on a simple ride up the lane from our farm house.

It was the sort of bike wreck that happens all the time. The rider usually gets up, dusts off, wonders at the clumsiness of the mishap and mounts the bike to ride on. Somehow when my sister Jeanne crashed that time, her head struck the packed dirt just so and she was knocked out.

I recall her lying on the sofa in the living room of the farm house for what seems like a couple of days. I have a vision of a cool, damp cloth on her forehead, but that may be because that was our mother’s go-to remedy for just about any ailment any of us kids suffered in our growing years. Eventually, my sis recovered with no apparent lasting effects.

(I think we might have taken Jeanne to a doctor after a day or so, but I might be thinking of my little brother Kevin, who broke his arm throwing a rock and didn’t get taken to town to see a doctor and get a cast for two whole days. “Nobody breaks their arm throwing rocks,’’ my dad said several times before we broke down and took the kid to see Dr. Holland.)

Jeanne wasn’t, of course, wearing a helmet when she rode her bicycle. Nobody wore helmets in those days. That seems strange, and pretty unsafe, when you consider how easy it is to crack your skull on a paved bike path or a curb on your own familiar neighborhood street. My friends and I pedaled madly all around town without helmets, never thinking a thing of it. Even my mother, as safety conscious as ever a mother could be, didn’t think of helmets when she told me to be careful out there.

I imagine a person could go online and find one of those memes that would say something like, “Like and share if you grew up riding your bicycle up and down the side of Pike’s Peak without a helmet and lived to tell about it.’’ If so, that would be another example of why you shouldn’t believe everything you read on the internet. It’s goofy not to protect your skull while riding. The thing houses your brain, and it takes only a moment’s inattention, a rock in the road or the carelessness of a passing rider to throw you to the ground.

Our older son, a fairly accomplished bike rider who has a passion for riding mountain paths in Colorado and the hard rock trails of Moab, Utah, was wearing a helmet on a casual ride back to Chamberlain from Cedar Shore awhile back when he hit a patch of gravel and took a tumble. It might have been a 1 in 100 chance, but when he landed on his back, the force of the fall whipped the back of his head onto the pavement. His helmet cracked, but it probably saved his life. He spent several months recovering from a concussion.

I went over the handlebars of my bike as I crossed the Missouri River bridge a couple of years ago. I had slowed as another bike approached, and my handlebar caught in the woven wire barrier that edged the bridge. I didn’t crack my helmet, but without it I’d sure have taken a nasty knock on the forehead.

Our daughter-in-law, who wears a bike helmet, crashed earlier this month while riding in Colorado. Her group was pushing the envelope a bit, riding a trail that included several jumps from one flat rock to another. She went head-over-handlebars, cracked some ribs, smashed up her wrist and hit her head. She’s had two surgeries on her wrist, and her ribs still ache, but her head is intact.

Here’s something from the Department of Public Safety: Head injuries are the leading cause of death in bicycle crashes, and 2,700 children suffer serious head injuries every week while biking. The same source says the safety message, “Don’t Thump Your Melon,’’ came into use in 1994. It may be a silly saying, but it makes safety sense.