Here are the mountains at Hodaka; you're seeing from far away the view that tourists flock to gawk at in Kamikochi. Look for a discussion of that trip in a future page on this site (and a brief mention on the Alternatives page)...

The short route back is to bomb straight down along the highway (route 158) into Takayama. The road is fairly wide and, though it can get crowded, not bad (except for the tunnels; see below) but it’s not all that interesting, either... though after where you've just been, nothing would be.

However, you should be prepared to cycle through the long Hirayu Tunnel (2.4km). If you’re planning to go not to Takayama but to Matsumoto, you should know that the middle section of this road (roughly the middle third of Route 158 between Matsumoto and Takayama) is one long series of often very long tunnels. Most of them have very little shoulder, and even when there are walkways, they’re not really wide enough for you to walk with your bicycle comfortably and safely (and in two of the tunnels, there are obstructions on the narrow walkways so not even walking on them is possible). There are regular express buses that stop at Hirayu, and these longer-distance ones (for example, the ones that go all the way between Matsumoto and Takayama) have luggage space down below, so bagging the bike and doing this section (from Hirayu to Matsumoto/Takayama) by bus is an option (and in at least the case of Matsumoto we actually would recommend that for most cyclists). If you do decide to cycle through the tunnels, make sure you have VERY bright illuminated front AND rear lights and wear bright clothing to make yourself as visible as possible.