I went out today for a long bike ride; mostly along the Ridgeway where it crosses the M4. I found 42 caches, but I had a lot of trouble with my rear inner tube. It kept creeping round, and in my experience, that leads to a valve blowout when it gets bad enough. And sure enough, that's exactly what happened. It's a failure that can't be fixed with a puncture repair kit. Fortunately, I carry a spare inner tube, and that kept me going.
I really have to solve this problem of inner tube creep. I tried talcum powder, but although I have a very nice smelling inner tube, it hasn't fixed the problem. But I have another idea, which I'll try tomorrow,