Just to let you know I have over the last 2 days done 2 15 mile timed runs. I have done 41 mins 28 secs and 40 mins 54 secs which I believe to be almost bang on 22mph so thanks for the advice everyone, now the next 2 years will be working on getting my marathon time down to the low 2hr 40s and my cycle time at 22mph upping the distance to 112 miles ultimatley.