Mine is in very tight, and I have a hard time getting it out with my hands, but when I least expect it, it comes flying out (of the wrist mount). The bracket is very stressed and there is little engagement so when it vibrates just the right way it’s gone. Maybe some brackets are more prone than others, but I’ve read dozens of threads on many boards about people losing the unit with this mount. When I train I throw a tie-wrap over the whole unit - not applicable in a race. I can’t say that it will fly out of the bike mount if the bike is jarred because I lost confidence in the mount with the wrist version and haven’t tempted fate on the bike. My next test is to thether it with fishing line to the bike and see if it stays in.
Before tonight’s ride I would have agreed with those who say their Forerunner snaps in too tightly to pop out. I changed the pins to the ones that came with the quick release kit and had never had a problem. Well, tonight I was going down a hill, hit a bad place in the pavement and out pops the Forerunner. It goes skipping across the pavement at about 30 mph and into the ditch. It landed black side up, so I had to search a long time to find it - I thought it was lost.
The Forerunner is a little scuffed but works fine. The quick release kit is back in the bag and going to the classifieds.