I grew up riding and not wearing a helmet, because people just did not wear them. We also had steel dashboards and no seat belts in cars. I have had more MTB and cycling crashes than I care to admit to. Let’s just say I still crash 2 to 3 times a month and I have been riding road bikes and MTB’s for decades. I like to push my limits. My point is, from my experience, if you are going more that 10 mph, wear a helmet! They are light, cool and comfortable. Plus they keep the perspiration from dripping into your eyes. It is one less thing to think about when you know you are going down and there is nothing you can do about it.