Beginning from the bottom of Purisima Creek Trail, Harkins Ridge Trail packs in 1500 feet climb in 3.2 miles, average incline of 10%. It is needless to say that this is evil. Probably the hardest climb around, with several hike-a-bike (15-20%) stretches and sun exposure. It is worth the effort and will soon be forgotten because you get to do Whittemore Gulch Trail a second time. The last 0.6 miles is nice and easy singletrack with one technical rocky section.