Analysing terrain data
The exposure grade describes the potential consequences of falling or slipping off the path.
Low Exposure: The path is on completely flat land and potential injury is limited to falling over.
Medium Exposure: The trail contains some obstacles such as outcroppings and rock which could cause injury.
High Exposure: Some trail sections have exposed ledges or steep ascents/descents where falling could cause serious injury.
Extreme Exposure: Some trail sections are extremely exposed where falling will almost certainly result in serious injury or death.
Thunder Mountain near Kirkwood, California is known as a relatively mellow peak hike—which means that it makes for an excellent mountain peak to summit on your mountain bike! Rocky singletrack that's no problem on foot makes for entertaining rock garden riding on a mountain bike.
Make no mistake: the grunt to the top is still strenuous.
But that steep climb rewards you with a superb descent! The descent begins with beautiful ridge top riding, with wide-open views in all directions.
The soil is sandy and loose, interspersed with sharp rocks that look volcanic in origin. After dropping off the ridge, the descent picks up in earnest, with some portions of the trail being bench cut into the side of the mountain.
The fall danger is quite significant through the bench cut sections—while the trail tread is wide, it would be a long tumble down the mountainside! Lower down, the steepness of the mountain slope mellows out, allowing you to really open it up and rail through the flowy, dry singletrack! In the middle portions of the trail, the singletrack swoops through wide-open alpine meadows. Eventually, this flowy track drops back into the forest.
Some of the lower sections of the trail actually hold bigger rocks and gnarlier rock gardens than the above treeline portions.
Here, the rocks are more rounded and boulder-like, with a few big up-and-over moves. There are a few different ways to climb and descend Thunder Mountain.
The route mapped here includes a little car shuttle via the highway to get you some free vert.
Alternatively, you could pedal up the highway, ride from the upper trailhead as an out-and-back, or if you’re truly masochistic, ride up from the lower trailhead.
However you choose to ride it, Thunder Mountain serves as a rewarding and surprisingly-rideable mountain summit. Sources: https://www.youtube.com/watch?v=Qe1eUxmWLoQ https://www.youtube.com/watch?v=6e01y7cNWtY