Woah, I haven't bumped this thread in over three months! There was one I didn't write up here, on the back wheel of my commuter; it started losing air in mid-February. I took the tube out and held it under water, stretched every inch of it this way and that way, couldn't find the leak. Changed the valve and put it back on the bike; but it continued to lose air. Early March I took the tube out again and held it under water again, and this time I found the leak. Patched it and problem solved.

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Anyway, went out to the bike shed at 4:45 am today and found the front wheel of the commuter bike flat. I rode another bike to the station and just patched the tube now. 32x700c pasela compe tire, no Kevlar but it had a flat guard in there. Puncture in the side wall, couldn't find the cause. Patched.