meyers66

Hi,
I live in Ping Chen City Taiwan. I usually cycle around Guansi, Hsinchu County because of traffic. I like this area because there are many cyclists and car drivers are aware of us. But I still take every precaution to be visible using a helmet mirror, bright shirt, and rear/front blinking lights during the day even. Expect to be pissed off by some of the stuff you see on the roads. Roads are rough. My tires are Conti Tour Plus 700x32 and work great. Also carry a first aid kit.
Many of my friends won't cycle here because they think it is too dangerous. It is dangerous because of the poor driving skills of car drivers. When I see crazy driving in my mirror I ditch.
There are books on cycling around Taiwan in Chinese. You can also check forumosa.com, Giant, and Taiwan tourism agency. Taiwan is pushing cycling big time. Some trains assist cyclists. Check "Taiwan in Cycles" blog.
I would focus on the East Coast between Hualien and Taitung and further south. These are famous for cycling. Taiwanese are really friendly. You can buy water everywhere it seems.
If you are going to cycle the west coast I recommend regional/blue highways.

My friend lives in HK and he has a carbon bike he doesn't ride. The roads in HK are very narrow and the car speeds are high. There is simply little room for error and no shoulders. Public transport is excellent. I suggest hiking the trails instead. Lama and Lantau Islands can be nice for nature.

Give yourself time to get used to the heat and humidity. Think 70-90%. I recommend Spring and Fall seasons because of moderate temps but you will see some downpours.

When you get frustrated try to remember "Taiwan is for the Taiwanese to be comfortable, not the foreign visitors." Substitute any country in the quote.

I don't know Hokkaido but want to go.