[QUOTE="Nev Gml"] OK so not sure why you're calculating the falling velocity of a 30kg weight but I'm sure your calculations are all correct. How does that relate to a person stepping off a bike and stepping away with a cord still connecting the jacket to the bike? Assume that it's not a vertical drop, and their velocity doesn't increase. Nev..[/QUOTE] I was replying to.... Yes you probably have it wrong. You were probably misled by other people who were wrong. The website states that 30kg of force is required to activate the 'ripcord'. That's an awful lot of effort before you actually do any harm. 80kg (rider) falling vertical 600mm (does the website say how long the lanyard is?) on a static system could pull about 3.2Kn. There are lots of variables to be included but saying that a fault is not possible either by deployment when not required or by failure to deploy when required based on a "30kg of force is required to activate the 'ripcord'." statement from the distributers website seems very.... trusting.