my 2nd one learn to ride at nursery, one day I turned up to pick him up and he was pedalling this tiny bike all on his own. My eldest didn't seem interested, but eventually learned the same way I had - you push them by the seat until they gather speed, then at some point let go.
The method involves a few falls, which is why I favour grass surfaces these days (my younger brother back in Peru wasn't so lucky; come to think of it, neither was I - it was pavement for us in them days). So I took No.3 to the park a couple of weeks ago, and gave it a go. Long overdue.
The good news is that she did get to ride on her own. We just run out of time as the weather closed in, and have not had the chance since, so next spring we'll have to try harder, for longer - so that she can reach that tipping point of self-belief that enables us all to carry on when our senses tell us we shouldn't be able to, without anyone else holding on to the back of our seat or rack.
Come to think of it, how handy reaching that tipping point would come in other spheres of life.