Trying to figure out a bad bike accident, please read!

[Markymark]

The original poster has not been back since his initial flurry of postings.

Maybe he's with his dad?

 

[Profpointy]

I'm not a doctor, but i don't think he will remember. We store things in our short term memory, then some of those things get written to long term memory. It's common after a blow to the head to forget the minutes just before and after. It's not a sign of long term or serious damage, it just means that the short term memory never got stored, so it's gone for good, even when he makes a full recovery and gets all of his memory back.

A friend of mine was "doored" and witnesses reported that she was alert and talking immediately afterwards. She says that she was unconscious. What almost certainly happened is the witnesses are right, but she didn't lay down the long term memory so she believed she was out. Even before the accident, she has little memory, except for a single image of an open car door. So similar to your dad, but with witnesses, so there is no mystery. That was the extent of the damage to her head, so she was not nearly as sick as your dad, but she recovered completely.

I concur with that. My ex-Mrs had an off and ended up in hospital (recovered fairly quickly) and had concussion, cracked cheek bone and facial injuries, but had and has no recollection of the day. We guess that she'd been clipped by a vehicle, but we've no evidence to back this up other than generally being unhappy with close passes from a regular bus on the route - as it's hard to imagine a an off without that or a mechanical of some sort.

For the OP's dad, I also agree that the chain-off as shown is unlikely to have locked up the wheel. It could have come off afterwards, or the rider could have clipped the curb whilst distracted by the chain off. So plausible causes I can think of are distracted by looking down (at chain, gears, whatever), or clipped / v. close pass causing a wobble, or some kind of tank-slapper type wobble this latter is rather unlikely but not impossible.
I don't know if the gentleman is elderly so perhaps some kind of faint / funny turn is conceivable - unlikely but not totally impossible.

 

[Smokin Joe]

Maybe he's with his dad?

Apologies to the guy if I'm wrong, but it hasn't got the ring of truth about it.

 

[Globalti]

Well he hasn't asked us for cash yet....

 

[glasgowcyclist]

My last bike used to slip the chain off the big ring fairly regularly and it never once caused me sufficient difficulty to cause a crash. At worst I'd just stop pedalling and bring the bike to a halt before remounting the chain. Eventually I was remounting the chain without stopping; I'd simply drop the shifter to the middle cog and gently turn the cranks to feed the chain back on.

My guess is the chain came off as a result of the crash, not before.

GC