Hardest bike climb route in the world.

Mauna Kea is a dormant volcano on the island of Hawaiʻi.From the beach in Hilo to the telescopes at the summit it’s 4,200m of altitude gain in one continuous climb of nearly 70km. The first section is 44km long with a steady, 5% average gradient, while the second part is 22km with a large variety of gradients (up to 20% some places) that average out at 10%, and including a 7km gravel section.