This is a moderate climb with excellent views of Mt. Rainier, Adams, and St. Helens. This is the easiest route to the summit and the only viable one in the summer. The rock is loose but not a complete scree field. Pro is sparse to non-existent aside from the sturdy tree about 3/4 of the way up, but the 4th class terrain makes the route do-able with moderate risk. The beginning 200 feet or so can be protected with a fixed line from a sturdy tree. The rest of the climb is 3rd class from there.The route will be snow-covered in early season (likely still possible to ascend). Wait until around August for a snow-free ascent.
Take the Pinnacle Peak trail starting at Reflection Lake to the ridgeline of the Tatoosh Range. From the ridge follow a climbers’ trail as it winds its way west to Lane Peak. The 4th class section of rock starts on the east face of the peak approximately here: (46.7577816, -121.7523414).
A sturdy tree about 200 feet up can be used to attach a fixed line and/or rappel. Use a 70m rope if you want to rappel to the ground from this tree, or down climb. Not worth bringing a trad rack aside from some slings for the tree.