Excellent ride Joe! you stayed near threshold, which must be around 180bpm for most of the ride. The first 10 mins you spent adapting to the effort level which is what many riders do. A half hour 'warm up' where you do the adaption before the race might help there. Here's a typical warm up routine http://coach.dancoy.com/archive/tt_warmup.html
I did warm up... but the first 10 minutes had a whole load of enormous potholes and a lot of slower riders in my way. I should have started at the front.