I suspect

I suspect that the first second is the hardest. Learning to trust that you are not going to fall over. Once you get past that, the second second must come easier, and after a few seconds, it's just a case of keeping it going.

Boo has just transcended the first second, perhaps two. This evening we went out to the nearby dentist's parking lot (where there is lots of shade!) and despite the heat, LOML and I took turns running along holding her upright on her bicycle, and letting go when she felt stable. And by the end of twenty minutes (which is all we could take: it is not just hot here right now, it is hot!) she had managed lots of times to ride for a full few milliseconds. And then on the way home, while Skibo and I went on ahead, LOML helped her on the sidewalk --- just outside our house, I heard LOML calling me from behind: "She's got it!" And sure enough, she's got it! The first second! Now the seconds will come easier, and before we know it, we are going to be terrified about her on the roads every second of the day!

Yours, on balance,
N.