I'm not necessarily ATGATT... "All The Gear All The Time" for you non-riders out there...
While I do believe in "dress for the slide, not the ride"... Having lived in AZ, CA, TX, NM, FL etc... and being a large man who generates a lot of body heat... avoiding heat stroke is sometimes better risk mitigation than heavy abrasion resistant clothing.
... but a helmet? ALWAYS.
I've been down, HARD, without a helmet, when I was in college... I am never doing that again.
I got really badly upset about something, and rode over to a friends dorm to talk about it (I lived off campus).
Yup... already setting myself up for bad things to happen.
While I was there, and still very upset, I walked out the door without my helmet, and went for a ride to try to clear my head.... Rather than go back and get my helmet, I stupidly got on my bike and rode away... I even thought about it at the time, as I was getting on my bike, thinking "I should probably get my lid, but I'm just going to ride around the campus ring road... it's not like I'll even be in traffic or on a highway... I'll be fine". DorrisWedding ivory and beige prom party wears
I wasn't.
Maybe 90 seconds after thinking that, I was half way around the 2.7 mile campus ring road...
I was hurt, angry, and stupid... I shouldn't have been on the bike, never mind without a helmet...
I hit a tricky bit of the road... a broad right off camber decreasing radius sweeper with a crest and a steep drop off at the apex, into an off camber left right left ess... almost a chicane going into the straight... with a dip at the bottom out of the downhill, right at the crossover point of the esses into the straight.
It's a very difficult section of road to ride under the best of circumstances... and I used to like to ride it way too fast... risk sharpens the mind and all that.
Well... I probably hit the crest at 75... speed limit was 25... nailed the esses and was setting up for the straight when I hit the dip...
It had rained earlier that day, and the day before, and quite a lot of sand had washed into the dip and accumulated there and for a few feet down the road...
You only get so lucky, and I'd used up more than my share already...
When I hit the sand, I was ok... my rear started to slide out a bit, but I caught it, and I was starting to recover, when my rear wheel locked up.
... we figured out later that when the rear tire finally got traction, something in the gearbox sheared off and jammed the works, which locked the rear wheel hard (abd turned the gearcase into a bucket of metal pieces)...
...and I low sided into a slide out, heading straight for a joshua tree at about 60mph.
Thankfully I realized what was going on, and as I was starting to slide out, I managed to get out from under the bike.
... and thank God, I at least had a good solid leather jacket on.
I slid and rolled what we later measured as 147 feet.
My jeans were basically sanded off me by rhe road, as was my right shoe.
My right arm, leg, and hip, clavical, and most of my ribs had stress fractures in all of them... no clean breaks thankfully. I strained and tore a bunch of muscles and connective tissues.
I broke my nose, and had several small stress and impact fractures on my head (jaw, ocular orbits, and the right side back "corner" of my skull).. but nothing too bad, nothing permanent, etc...
They weren't so bad that I went to the hosptial for them... though I should have... There was a lot of swelling and pain, but it healed after a few weeks to a couple months... I only found out about most of them later, when I had xrays and a flouroscopy session for something else, and there were new lines of healed bone indicating breaks where there hadn't been before.
I barely even had any road rash.
Hell... I didn't even have a concussion... Which itself is a damn miracle.
I was shaky as hell, and in a bunch of pain, but I was able to get up off the road, walk over to the bike, and survey the damage.
The bike had gone straight into the joshua tree at high speed. It hit the tree with enough force, that it not only crushed the wheel, it embedded both front brake discs into the crank case.
If I had gone down under the bike...
I'm catholic... I honestly believe the only way I survived was God taking a hand. There is no way I should have survived that, never mind had so little damage.
I actually walked back through campus.... it was a semester break after hours on a weekend, so there wasn't anyone there to help, until I got back to my friends dorm room.
... never rode more than a few hundred yards without a helmet since, testing a repair in my own driveway or summat like that.
Like I said... you only get so much luck, and so many chances... and I've already used up way more than my share.