Nearly 2000ft of climbing on a 14 mile ride. Mercy.
I now consider that I have NEVER done mountain biking before today. The ascents were brutal, so much tougher than road biking and the descents were frankly terrifying. The bike was remarkable, I was using a single finger on the hydraulic brakes which were astonishing and I was slamming into rocks that I would have assumed would destroy the bike and it safely carried me over them. It took a lot of nerve to follow the instructions I was given to just relax and let the bike follow the path it wants to, especially when the bike chooses to aim at a huge boulder.
I have never come off a bike so much in a single ride ever before, I also had my first clipless moment, into a hillside of ferns. I appreciated the rest. I managed to stack the bike on a fast descent, I think I hit a large flat (wet) boulder while leaning into a corner. The first hint something had gone wrong was when I noted that I was running down a rocky hillside minus a bike. I had to climb back up the hill about thirty metres to retrieve the bike. I heard it CLANK on a big boulder and it landed on the transmission side, the bike I was lent was worth about £2500. I was sure it would be destroyed. It was fine. Amazing.
Mountain biking is like parenting a toddler - long periods of brutal grinding hard work interspersed with brief moments of sheer terror, with a guarantee that you will often get wet and covered in brown stuff.