Yesterday, I did this 2 x 6,000 m test proposed by Coke and Pau from our Barcelona Dragons Triathlon Club and the result was:
First 6K Avg. pace = 4'41''
Second 6K Avg. pace = 4'26''
Difference = 15''
...therefore, I should be running slower then, my tentative goal should be: SUB 3H30'
Pace between 4'45'' and 4'56'
Possible finish time = 3h20'26'' but more realistic 3h28'
...at the end both times look to me today VERY AGGRESSIVE!! and not reachable...but I am going to follow some of my team members suggestions and start with 3h30' pace maker and, if I feel great last 5K try to push hard to achieve a good time!