Based on the new timeline information that police released in September (posted upthread) and the statement from the lawn watering man, I think that the girls did cycle to the lake area. Mr Carpenter, on Lake Avenue, said that Elizabeth and friends regularly cycled to the end of his road (bordering Arbutus) turned around and came back ... went home. He said that he recognized Elizabeth as a friendly, talkative girl cycling past his house (while he was watering the lawn) on July 13 shortly after noon. It sounds like Elizabeth and Lyric may have ridden to the South end of Lake Avenue - which is along Arbutus right near Maiden Lane, and vanished around 1:00-1:15 PM.
The next sighting of their bikes, with the girls missing, seems to be at 2:00 PM where the bikes are at the gate and children were no where to be seen.