The weather forecast for Sunday looked favourable, with little wind to hinder his run, he said.
A wheel puncture, an injury, or Audrey becoming too restless were the unknowns on race day, he said.
"I'm in good nick at the moment ... And [Audrey] is used to being in the pram. There's a 50 per cent chance she will go to sleep."
The run was also a celebration of the time spent exercising with Audrey and elder daughter Lucy (5).
"We've clocked up around 15,000km in the five years I have had the pram," he said. The run would also promote the benefits of sustainable transport, he said.
If he broke the record, he expected many retired runners to dust off their trainers and have a crack.