Even with snowmobiles out there, there's a lot of deep soft snow that would be tough on a normal bike. The Spring Mill Pond hill I could climb, but coming down the sled tracks scattered and I walked most of it. Blue loop was best, I almost endo'd on the Yellow when I encountered some trail runner tracks half way. Those were nasty, past 4" deep, made hills impossible to climb. I barely did a half mile in twenty minutes or more. Finally a snowmobile passed through just before I got to the Kensington road bridge, then I could start riding at speed again.
Snowmobiles pretty much ignore the new section this year descending alongside the road. The path they are making has a pretty dangerous ending. I followed it, but walked down the hill. When they get to the road, it's a very steep descent. My fear is I would get too much speed ending up on the road and hitting a passing car. Either way, a couple years ago I saw a sled almost slide off the new section. Seems there's no longer any safe way for them to get down off the hill and continue on. Tough riding that sled section, lots of low hanging branches make it impossible to ride though in some spots.