I wrote this after 5 time did my (lonely) ride on this track.
Sakurajima mount located on the center of Kyusu island, surrounded by the sea (so it also called sakurajima island, as we know geograpically Kyusu has a huge gulf, yes, this active mountain is like on the center of Kyusu. (see on the map)
From kagoshima, everyone can reach this island by local ferry. These ferry, as a general transportasion, is very comfortable and appropriate for every vehicle especially (road)bike. The fare for 1 bike 1 way is 270yen. Not too cheap but i think is worth to pay this amount for beautiful scenery of sakurajima mount, kagoshima port, and the sea between with its kind of solitude of the diswave sea, even only 15 minute cross. (Because of the sea actually is a huge gulf, there is no wave, very 'calm' sea).
The sakurajima ferry port face kagoshima at west direction, we can choose any direction to start to ride around the island. To the left/north or to the right/south.
1 time round: 35km, just follow the main road. Most of the track is the seashore outside, foot of the mountain inside.(depend on which side you rode. I prefer start to north because nearer to the sea, just beside). Awfuly beautiful. Some kilometers are break through the hills and the forest. Rolling, 50% of the track is hill climb and down , in average 3%-6% grade, with short and long variation. Lil bit strong headwind sometime (from the sea and the mount) also if the active sakurajima blow the ash (not always, and not a big deal). Good asphalt, quiet from the cars, and no red light stop signal, hmm maybe from 35km only 2 red light.(the last two is really make comfy for ride!)
There is a park with foot onsen just beside the ferry port, i like to go there before cross back by ferry about 15-30minute foot relaxing in onsen. Enjoy pain, enjoy life =]
Here some image i took there, sorry for narcism contain.