I've run here a few times and it's always really kicked my arse. I have now mountain biked here and it also really kicked my arse. Great workout pushing my bike up insanely steep and rocky trails that were impossible to ride up. Slow going on most of what I could ride, with the exception of a fun downhill at the start down a dirt road and another, more technical descent off the summit along the Horse Trail and then the Ring Trail back to the car.
I forgot my Garmin so I downloaded the CarioTrainer app on my phone (Android). It seemed to work pretty well, though I screwed it up at the summit and didn't record the trek down back to the car, so I'll have to guess at my stats a little.
Mountain biked around 4.1 miles @ ~5.0 mph/avg (~23.0 mph/max).
Technical trails, one section of dirt road.
Upper 50s, sunny.
Shorts, short sleeved shirt.