This road starts on the east side of Munising and ends at Grand Marais. Just look for the signs for H58 and Picturred Rocks National Lakeshore. Same with the reverse, you cannot miss it
Although much of the road is just going through the woods, there are some scenic overlooks and one fairly short stretch runs right along the lake. You should take the side trip (12mi roundtrip) up to the Pictured Rocks overlook. You'll get great views of Lake Superior which according to the National Park Service is "the largest, deepest, coldest, and most pristine of all the Great Lakes".
This is what makes this the best ride up in the UP (I hesitated to recommend it!). The last stretch was just completed about a year or so ago and the pavement is in great shape. There are some twisty parts and lots of sweepers. I was told that the road can get crowded, but I only saw about three cars and a dozen bikes. There was only one curve that had bits of gravel on it.
No gas stations and only one restaurant/bar that I passed. There are one or two "rest areas" with facilities. Pictured Rocks National Lakeshore is national park along the way (Pictured Rocks NPS website) - the NPS website describes the park as offering: "Sandstone cliffs, beaches, sand dunes, waterfalls, lakes, forest, and shoreline beckon you to visit Pictured Rocks National Lakeshore. Hiking, camping, sightseeing, and four season outdoor opportunities abound. The Lakeshore hugs the Lake Superior shoreline for more than 40 miles. Lake Superior is the largest, deepest, coldest, and most pristine of all the Great Lakes."
Motorcycle Road Additional info
I took this ride toward the end of a weekday and found it almost empty. The ranger outside of Munising did say it can get crowded. My guess is if you go mid-week, that would be the best.