A freshly brazed coupler
Had a bit of a discussion with a customer the other day about the relative benefits of traveling with your bike using a rinko system versus installing S&S couplers in the frame.
Rinko has come into the view of people here in the U.S. mostly through the efforts of the fine folks at Bicycle Quarterly. It is a method of packing your bike down as small as possible using as few specialized components as possible as quickly as possible. You do need to be able take the fork out of the frame. With a threaded headset you can use a rinko specific headset or one modified to be adjustable without a headset wrench. Other than that the rear fender (which you need to be able to split at the seat stay bridge. Not applicable on bikes without fenders.) it's all about taking everything apart and strapping it together in the correct manner. You would then shove the bike into a bag for ease of carrying or as required by your mode of transportation (say onto a train in Japan in order to be able to carry the bike on with you). All in all it's a pretty ingenious system. You make the smallest possible package out of your bike. There is a certain almost ritualistic methodology to disassembling and reassembling your bike. It's rather beautiful.
The downside to the rinko system is that there isn't really much call for it in the states. There isn't really any situation that I could think of that it would be advantageous to pack your bike up like this vs. another method. Traveling by train in the U.S. usually involves rolling your bike on in one piece (most commuter transit systems) or packing the bike into a very large box (on Amtrak you only need to remove your pedals, drop the saddle, and turn the handlebars, the boxes are that big). Ferries will inevitably let you roll your bike on. Most folks who drive places with their bikes have bike racks. And packing your bike up rinko style will not get you below the oversized baggage limit on an airplane. The frame itself is dimensionally just too large. You would need to make the frame smaller in order to pack it small enough to not incur oversized baggage fees.
Here's where couplers come in. With couplers installed you can break your frame in half, remove most of the parts, and stuff everything into a case that measures 26"x10"x10". This is the maximum size something can be and still be considered normal sized luggage. With oversized baggage fees these days you can save yourself up to $300 per round trip. That's not insignificant, the added cost of the couplers and accessories can pay for themselves within three or four flights.
Not that there aren't some downsides to the coupler system. It does add a little weight. About 6oz. per coupler. The cost to get into the game is pretty steep (around $1300 for the coupler install and all the fixins). There is a bit of time on each end to break down and put the bike back together (around 30-45 min. on each side). And the packing process can be a bit daunting at first, but once you figure it out you're all good.
So it all comes down to what you want to do with your bike when it's broken down. If you are just looking to make it smaller, go rinko. Your bike will take up a lot less space. If you're planning on doing a lot of train travel in Japan, go rinko. If you are planning on going to Japan via airplane (or anywhere else for that matter), get couplers.