I'm requiring of some tea.
I was cheerfully cycling along, as you do, when the back wheel all-of-a-sudden locked solid

At 20 mph

There was a rending of metal as the rear gear hanger broke, followed by a 'Bang!' as the rear tyre succumbed to the frictive embrace of the tarmac and 90 psi escaped gleefully to rejoin the atmosphere. I kept it all upright, and just managed to avoid wrecking a perfectly good pair of undies

I now have no touring bike in a usable state, and a weekends tour starting in 160 hours and counting. I do, however have other bikes.
So, here's the thing. I'm aiming to do 3 days of around 40-50 miles. The first day starts mid afternoon (ie after work) and will involve some hills till I get nearer to Cambridge. The rest of the trip will be flat, in a Fen-like and Norfolkly kind of way. Ultimate destination is Kings Lynn.
I have a choice of bikes - a M6R Brommie, a 531 singlespeed, or the Carbon Uberbike with a seatpost rack.
Not sure which one to use. Some tea would be good while I ponder.