Thanks for the tips...
Yesterday I remembered why I'm doing this slightly loony project:
We stripped most of the bike down on the weekend, but the cranks and BB needed some tools I hadn't got, so we arranged that Elder Son would ask his boss to lend us a couple. He was a bit unsure about this for fear of making a mistake (Thanks schools system) but agreed to give it a go.
Yesterday evening he rang the bell and reported that he did have the tools, so I went downstairs to lend moral support. He'd already started, and looked up to say "Hi dad, I though you might like to see how this works" waving the mother of all BB spanners about. He took hold of the bike, instructed me to hold it "Like this" Swung the spanner, undid all the bolt while explaining how he did it, and finished job in five minutes.
Then he bounced up the stairs and announced to the world in general: "I can fix bikes..."
You can't buy that...
[Edited: Tenses mixed up.]
It is a lovely feeling that.