Cribed from the Annadale Night ride description for Oat hill.
Meet at Oat Hill Mine trailhead in Calistoga at 1030 AM. Intermediate technical level ride (some websites describe it as advanced). Reasonably tough aerobic and technical climb (4 miles, up 2000' if seasonal closure section of the trail is open it will be 8.2 miles to the top) followed by an exciting ~20 minutes of downhill.
The trail is rock and drains well, so mud / trail abuse isn't an issue. Helmets required, knee and elbow pads recommended. 5-6 inch travel bikes recommended as well.
We may even do it twice if fitness levels allow. Those that do not do it twice will be permitted to drink beer at the bottom.
We may go to Gott's Road house afterwards for a regenerative burger and cerveza.