Wife and I took the trail off the Columbia Trail on bikes. The trail is marked with a huge sign, and blazed in yellow. A few feet onto the trail, there is a left spur that takes you to a view of the dam below (worth a visit!). The trail goes right down the hill. The first part was finished and bikable - the lower section had roots and some erosion so wife wanted to walk it. At the bottom you see the steel works building. The trail goes to the left over a refinished bridge. It passes through an easement provided by an existing industrial company. The trail was covered with a thick mulch of chips and small branches - it was bikable but barely. Past the easement the trail turns left, and after a few hundred feet comes to a T intersection - the full trail appears to go right - we went left towards Solitude house.
I had seen two maps of this trail - one has the trail marked with yellow lines overtop a satellite image, the other in red over a map. Both show the trail going around Solitude lake - I found bits of a trail but what I saw was not bikeable. Also, both show a crossing over the dam - but no crossing exists. So, we decided to get onto River Road at Solitude Dam, and proceed north on it. Good choice!We took the road to Califon and returned on the Columbia Trail.
Again, the both trail maps show a crossing at the top of Solitude Lake, and I was looking for one, but never did see anything. There was one spot where it appeared shallow - maybe 6" of water - but I wouldn't ride a bike across. If you did get across, you would not be able to make a loop anyway
Based on what I saw, this trail is really meant for hikers - even though one blurb I read mentioned biking. One nicety is that the connection we took permits one to park at the Columbia Trail head, and get to Califon on River Road, then looping back on the Columbia Trail. During our ride at 10:00Am, not a single car passed us on River Road. Half way to Califon the road become gravel, then it's closed to cars for a mile or two. We arrived at the center of Califon without having had one car overtake us!