I have to say my biggest ever scare was dh, whilst I was pregnant with ds1, he did not arrive hone from his regular 20 mile, off road bike ride, and pub crawl with friends. After midnight I rang the last pub stop, they had seen him leave an hour earlier, so went searching to no avail. He finally showed up a few hours later, filthy, with a few cuts and bruises, completely unaware of all the fuss...He had fallen off and lost two hours somewhere in the woods presumably at first medically unconscious, then "just asleep". Scary stuff!
Boys have all got cycling scars..the very worst was an over the handlebars injury on ds3's willy when he was 7...luckily it happened just outside the gate. Husband still shudders at the thought of it, bless him, it had to be superglued back together in a&e
Hence, they all have to have a phone...even though it is not always in reception, and it is useless if they are "asleep" in the wood!