Tioga Pass, the only route to Yosemite NP from the east. 20 km at 5% belies the middle 8 km at 8% all above 8000 ft elevation. I rode it conservatively, partly because, duh, this is hard, but also because it was the most spectacular mountain pass I have ever had the privilege to ride. Wish I had a camera that could do this place justice. Thanks to @visitmammoth and @mammothcrib for this incredible opportunity.