I had a GPS bike computer and I maintained 33km/h avs for bike and that was reached on first lap and maintained. Run felt very even, I was sow to start and maintained the slow pace. I certainly didn't feel like I fell in a hole I just could get going right from the start. Been doing tri specific training for about 3years after having done some riding and running on and off over the past years. That was my first Half Ironman so I'm certainly not experienced over that distance. Do 2-3 swims a week with a squad, 3 rides and 3 runs. Rides and runs are on hilly terrain. Do one interval session a week running, mainly shorter intervals of between 30sec and 4mins (do it with a group so just do whatever is the order of the day). Probably total about 10-12hrs a week.