Bicycled the Groveland Secondary Snowmobile Trail on August 9th, 2015. It's publicly owned by NYS-DEC, but it seems not to be maintained by them at all. The only reason it's not completely grown over is that the ATVers ride it against signed instructions, and that keeps the grass down.
The grass isn't the worst part, though. The problem is that the railbed didn't have all the ballast removed when the rails were ripped up. The entire way (mostly) you're riding on one piece of ballast or two or sometimes a short stretch of ballast. There's not a single section which is free of that kind of nasty riding. Consequently, I only rode it for 13.6 miles from Alexander to South Street Road. That's more than half, so I'm going to count this trail as being ridden to the extent anybody could.