These links will give you details you can keep or use (or ignore, if they are not useful for you). I am also happy to answer any questions you may have in the comments, to the best of my ability.
Bicycling in Tokyo will be different than where you've been. A few notes:
- despite all of the bicycling you see on sidewalks, you are legally supposed to be on the road
- police do not enforce this, and may not know themselves (!) so use your own judgment
- there are no mandatory helmet laws
- drivers signal decently here, and the hazard signal means pulling over to park
- taxi drivers are as usual the main menace
- its safer than it looks (four times safer than N.American cities)
- you have to pay about 100y to park in busy places: train stations
- there are bike shops everywhere, but most are limited (but fix flats for peanuts)
- bike theft of cheap bicycles is common, when people have had a few too many or missed a train (umbrellas too)
- ironically, a middling lock is enough deterrent, in most cases
Here's how to register your bicycle, which every resident in Japan is supposed to do (I have not...). It is useful for getting it returned if stolen, or to prove you own it if asked for proof by an officer (my bikes are gigantic, so this has never happened to me). This link tells you to go to the local police-box (koban) to do it, if it is second-hand, or have it done when you purchase a new bike in a store (more information).
If you are over 5'9" you're going to have a hard time getting a bicycle in your size. I brought two from home for that reason. You rarely find something big enough online in Japan. Some overseas retailers will ship to Japan, but you will get dinged for duties. If you are going to get one of the utility charinko/mamachari you see all around you, they come in two sizes based on a 26" or 700c wheel. Folding bikes are not allowed on the trains in rush hour, of course. You can take any bicycle on trains outside of rush hour, but they must be bagged in a rinkou-bukuro. 3000y cheap bags work well enough, but be sure your bike will fit. If you would like more information about bike touring in Japan, we can talk in person.
You can buy a basic utility bike for 10000y and up anywhere, but for something a little better, here is a link to a cycling club's list of bike shops. I am partial to Seo-Cycle and Y's Road. Both have many locations around Tokyo. For Y's, I prefer the locations in Ueno (map), and the bigger one in Shinjuku (map). Both, like many sporting goods stores here, have different departments on different floors or nearby buildings, so please ask them. For Seo-Cycle, there are two locations in the same Funabashi mall that has Ikea, as well as this location in Kotu-ku I have not been to (map). If you want something specific (fixed gear, touring bike, etc.) I can tell you where I have seen these sold.
As for where to bike longer distances, you are in some luck in Tokyo. Your first recourse are the 'cycling roads' along the levées by the Arakawa and Edogawa rivers on both sides of each (link to bike routes around Tokyo). The Tokyo/Saitama side of the Edogawa is the best, as it has fewer gate-obstacles to slow down your training. If you are more competitive than I, this group may be your cup of tea. Or this one if less competitive. Trains to the seaside or mountains get you into much better scenery. You may want to get a GPS, or a waterproof mount on your bike to use the GPS with your smart-phone, as you may have noticed it is simple to get lost in Japan.
I do a lot of hiking in the mountains here, especially the taller ones in Chubu. Again, please 'pick my brain' if you have any questions, but I'll give you these links:
- 'Hiking in Japan'
- Lonely Planet's 'Hiking in Japan' book
- Japan's '100 Famous Mountains'
- my favourite shops: Koujitsu-Sanso in Shinjuku or in Ginza; Kamoshika Sports in Takadanobaba.
I have not joined these, so can't endorse them, but here you are:
- Tokyo Gaijins (for profit)
- Outdoor Club Japan
- International Adventure Club, Tokyo
And bear in mind that Fuji is the worst mountain in Japan! It's the tallest, but it's a pile of cinders with overpriced and smelly huts strung up its side. Plus, you may be fogged in for the sunrise. Fuji 'looks good from far, but far from good'.