Doing the campground loop and then heading across the dam and then North to lot 17 is about 15 miles. If you are looking for additional miles with some good climbing (it's not single track) head North out of lot 17 on the grass service road, it will lead you to another gravel lot which will take you to the blacktop. Turn right onto the blacktop and then take the first left (gravel) and head North, this will take you to North Poosey. The North Poosey loop is all gravel service roads with some really good climbs, fast downhills, and long flats for recovery. If you aren't familiar with this area it might be best to ride with someone because there are a few options along the way. Finishing this loop you can double back to lot 17 and then continue South to your original start. This is roughly 27 miles total.
I hope this doesn't confuse you too much, feel free to contact any of us on the forum or my email is
mmbernskoetter@yahoo.comMitch