Could a brakeless 20" bike have fun on these trails? Not talking about jumping, just going fast and carving the dirt.
Doubt it, some parts are "smooth" but a very stiff framed bike with 20" wheels would be low on the fun scale. Most is fairly bumped from the winter of dear and bikes on the soft ground, with root sticking up across the path quite often. It's free though (till this Saturday when they start working the gate again).