They make better knives than bicycles too, imo. There's a saying among bike mechanics. It's often better to restore a bike, unless it is French. They used all sort of obscure standards on their bikes, which made them essentially unrepairable in the US back in the day. My experience in dealing with those hassles left a real anti-French bias in my mouth, which is to say that it is all the more noteworthy that the Opinel has earned my respect and loyalty. It's just a useful and functional knife.
There are only four parts to the Opinel: the handle, the blade, the pivot pin (hidden) and the lock ring.
The crude method I use to remove the lock ring is shown in the You Tube video.http://www.youtube.com/watch?v=PMI9MKuygIE
I use a small screwdriver as the pry bar.
Another method is to use a set of reverse pliers or to make your own reverse pliers by cutting down the jaws of a wooden clothes pin.
If you study the ramp along the top edge of the lock ring and how it engages the blade as it locks, it should be pretty self-explanatory to see how to file down the top of the ring so that the ring will spin more than 90 degrees. This mod really changed the Opinel's lock into something I trust a lot.
I once heard a speaker talking about computer security and he said all that a hacker is is somebody who can bend the computer to their will. A "hack" is old computer programming lingo for taking an existing computer program and modifying it slightly to better suit your need. A good modification would be called a "good hack". It's similar to hot rodding - the act of bending the car to your will.
The best advice I got about the Opinel is that it's a starting point for modification. It's the knife equivalent to a 1967 Mustang. When it was sold, it was pretty much understood that the buyer would modify it. Going the other direction, there is something a bit sad about an entirely stock Mustang in my mind. Same thing is true about a stock Opinel. In my way of thinking, my Opinel should end up looking different from your Opinel. They're meant to be hacked, hod rodded and modified to suit your taste.