I did the Brimstone Trail for the first time today. I started on Big Bend before I remembered that Brimstone had been groomed. According to the signs, it is 8 miles from the north boundary of Harriman to the end of the Brimstone grooming at Box Canyon. So my total distance was probably around 15 miles, a little over two hours.
There was a skiff of new snow on top of a good base. I was waxed pretty well with the 6-7 mix. The trail was quite a bit different than I expected. Rather than paralleling the river, it deviates to the west. It is fairly forested and has some rolling hills. Near the north end of the trail there is a very large clearing, probably about a mile and a half in diameter. This is undoubtedly the swampy area that thwarted the attempt that Thomas, Stephen and I made to ride mountain bikes from Ponds to Harriman years ago.