The lake is enormous, though people do make it around in a single day. But unless you're gearing up for the Ironman, you'll want to do it in two days. Only at the north end are there places where the route might be difficult to follow; consult your map carefully in these areas, particularly if you want to do the side trip to Lake Yogo. Note that unless you want to bypass the shore on a rather busy highway (route 303), you will have to do some climbing (to almost 400m) at the peninsula at the extreme north end of the lake. For your trouble, you'll be rewarded with some of the best views on the entire route. Elsewhere, this part of Shiga Prefecture has some communities that look as if they haven't changed for half a century or more. My advice is to get a detailed map and take small roads as close to the lake shore as possible. There are also short bikepaths here and there, though they go off on tangents and generally won’t help you get around the lake.