It's interesting to read that spec and compare it with the AliExpress adverts. 1621-4 wants the bag / vest inflated in under 200 milliseconds - 1/5th of a second. Most of the bags that MCN looked at (I'm not sure they tested any of them!) claim inflation times (roughly) in the 50/60 millisecond range. You're not going to get that with a CO2 cartridge borrowed from your puncture repair kit. In fact 1621 is more concerned by burns caused by the 'explosives' going off (and specifies a maximum exposure temperature). It doesn't even mention getting 'burnt' from low temps.

A lot of people (most, in fact, from my memory) picked up on helmets being a good idea long before they were made compulsory and wore them. I don't think airbags are in that category yet though. Sure, when you're flying through the air having hit a car and launched yourself over the roof, you'll be pleased to feel the airbag inflating around you but primary safety would suggest it's better not to hit the car in the first place. If you race (even on the road!) or do trackdays then (decent) airbags are probably a significant safety upgrade but whether they are for overlanding style riding, I think the jury is still out. The activation mechanisms are up there with self driving car technology - they work well under a few well defined and predictable / foreseeable circumstances but for average mixed conditions we're in almost more trouble than it's worth territory.

I've tested out a Helite Turtle vest, which is powered by CO2, and it inflates with enough of a bang that deployment speed really isn't an issue.

One of it's main benefits if you're off road would be that it holds your neck, so if you headbutt a bike or large rock you're less likely to do your neck in. It would also provide a little basic stab protection if you're in woods. However, for me, when riding off road heat is a major concern and they don't exactly ventilate well.

Both myself and my wife use Point 2 motorbike airvests, made in the UK and serviced every year by the manufacturers who clean the vest, replace the airbags, and test the system before returning it to the customer.

My wife did a little test of her own (Point 2 equine air vest) a few years ago by getting thrown in the air by her horse, and landing on her head fracturing her neck, back, and sustaining compound and compressed factures to both wrists.

You may think that in the circumstances that the airbag was a total failure then, but the inflated vest supported and stabilised her neck which is probably the reason I'm not a widower, or at best pushing her around in a wheelchair.

After 10 hours in A&E Emergency, several weeks in Critical Support, and several months recovery she's riding horses once more... and they say bikes are dangerous!

I've been using the airvest for about the last 9 years, and despite getting off the bike whilst still tethered I've not managed to set it off yet, it needs a good sharp pull on the tether to do so!

Wouldn't be without it nowadays.