(sorry if you're getting bored of this). Chris did indeed collect my bike yesterday, and seemed slightly startled at the failure mode. He also seemed relieved that nothing appeared mangled (indeed, he commented today "from your description I'd worried the rear mech had got bent, which would have been £50 just for the replacement part). This morning I took advantage of the 50p bus fair to get up to Girton and pick the machine up. It now seems happy once more...