One hell of a canyon. The more I look into it, the deeper it gets, man. A bit like the 60's B movie "Crack in the World".
Was in Halfords yesterday afternoon getting spare tubes to fix the flat (not yet knowing about the rim crack) and there was someone in with a nice Kona having repairs done. Looked like their back wheel was pretzeled. Overheard that on examination of the wobbly wheel to be repaired, the manager had spotted a crack right through the rim cross section – it was unrideable. The manager quite rightly told the guy this and that it was dangerous to ride the bike – basically he would need a new wheel. The guy was quibbling about the cost of doing this and just wanted it repaired, but quite rightly Halfords refused. The guy then wanted to ride it away. The mechanic took the back V-brakes apart so that he couldn't ride the bike. The guy tried to ride it the shop. I left the store after that because I couldn't bear to watch the inevitable happen.
I digress...
My wheel's rim walls seem thick enough, but they are being pushed out by the canyon opening up around the rim. These rims are going nowhere though. Also, the hubs are in a bad state. The wheels are about 23 yrs old now. They've seen action in the woods/hills/mountains of S & Mid Wales, traversed the high moors around Halifax and Huddersfield, spent half a dozen years in a damp cellar at my parents old place, and for last few years have been hacking back and forth commuting between Enfield and Wimbledon clocking up 165 miles a week. Time for all new wheels. And a good time to learn how to build my own.