Before read forward, make sure the transportation is valuable
I bought a folding bicycle in Kyoto 6 months ago and it cost me 35k yen(include accessories), I still need a bicycle in Tsukuba, so compared to sold it in Kyoto and buy new one in Tsukuba, I thought transfer it to Tsukuba is reasonable.
After STFG I found a bicycle transport service start at 7k yen, packing charge not included, and it's for ordinary bicycle not folding bicycle, I want to find a cheaper way.
Japan Post Youpack
Yes, Youpack can tackle with 170 size package, 10 cm larger than Yamato and Sagawa's express home delivery service. weight limit are as usual, up to 25kg. It will be delivered at the next day and you can specify delivery time in 2 hours interval. It also can keep your package for 10 days before delivery. If you can pack your bicycle into a compact cardboard box smaller than 170 size, Youpack are definitely the best choice.
Yamato(or Kuroneko) Yamato-bin
Differ from the Takkyu-bin, Yamato-bin can deliver package up to 200 size 30kg weight at the day after tomorrow, and delivery time specify are not available. Be noticed that Yamato-bin use their Volume Conversion Weight to charge for your package, which calculates as below:
L(m) * W(m) * H(m) * 280 = W(kg)
They will compare the VCW to the real weight and then charge for the heavier one.
As it's name, just a large size Takkyu-bin, up to 260 size 50kg make it prominent. Of course, their price are also prominent. What's more, they charge another 20% for bicycles and other unshaped product.
Find a cardboard box
You need to pack your bicycle yourself for all the services aforementioned, basically, it means you have to prepare a cardboard box.
If you still keep the original package, you can just put your bicycle in and send it, but the original package are usually not compact enough, they were designed for bicycle and accessories, so it might be oversize.
Buy a box(not realistic)
I found some shop on Rakuten selling bicycle boxes at unreasonable price, but if you can find a well-tailored box for your bicycle, it might be feasible.
Get a box from bicycle shop
Go to your local bicycle and try to get a fitted cardboard box for your bicycle. Basically those cardboard are trash to them and they have to pay for their disposal so they won't be annoyed to your request.
A handcrafted cardboard box(the hard way)
Yap, that's my way. I dropped the original package and can't find a bicycle shop in local area, so I decided to make a cardboard box myself. The boxes you can get from supermarket are usually too small, because the package of foods and daily amenities were designed can be carried by a normal labor. The biggest box I found was kitchen paper's package, 60 * 40 * 40 size. I extended the bottom and top then braced all facets and vertex and finally got a 84 * 60 * 40 size box.
Fill your package with cushioning
Use bubble wrap to protect the sensitive parts like derailleur, seats, handle.
You have to use cardboard to protect the touching point between bicycle and box. Not to protect your bicycle, is for your box.
Fill the rest space with newspapers, make sure your bicycle won't lingering in the box in transportation.
Call the service provider
Now you can call the service provider, or you can take it to their service center and get about hundred yen discounts.
Call service center days before
If you are not using a ordinary Takkyu-bin you'd better call them days before. e.g. Yamato-bin have to call the service center and they will ask the local branch and pick a time the call you back. You also can not request from website.
Stick labels correctly
You'd want to stick some warning labels on your package, such as This side up, Fragile, check the options on your order or just tell the delivery man.
That is all I can tell, good luck.