For more information on parking and access, contact the New York State Department of Environmental Conservation.
I biked the eastern section, between Greigsville (63/Genesee St) and Peoria Rd. It appears to be used almost exclusively by 4-wheel ATVs (except for winter).
I parked at the crossroads of Federal Rd and Craig Rd. Google Maps claims there is a trailhead at Dow Rd, but there is no parking there, not even enough room to get your vehicle off the road. This website says there is a trailhead at 63/Genesee St in Greigsville, but I can't confirm that, and the satellite imagery doesn't look encouraging.
As others have noted, there is considerable ballast, at least on this section. My bike has 4.8" tires, and I had their pressure at 4 psi. With that marshmallow tires setup, the ballast was still definitely annoying but not terrible. On the large majority of bikes, this ride would probably be bad.
The wooded setting was nice.
Regarding winter use: A ranger said snowmobilers use and even groom this trail.
I have walked from Griegsville to just shy of East Bethany. I appreciated the fact that the railroad bridges were kept in good shape for walkers. Loved crossing the Oatka Creek and other creeks on the trail. It is a shame that the rocks (ballast) were not properly removed. The places this trail goes are truly lovely. Livingston County especially. I agree with the other commenter that it seems the only people that go on the Groveland Secondary are the very folks that aren't supposed to: ATVers. I stuck with it because I can't resist a trail, and like the places it goes. If the rocks were removed I would give it a high rating. I wonder what would it take to get this trail improved.
Riding the ballast on these old rail beds is real exercise! Goes on and on....
http://blog.russnelson.com/bicycling/1439138714.html
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.
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