Something weird and slightly creepy happened this week.
It all started in an innocuous, if slightly annoying, way. Riding my bike home from work, I found that the back wheel was incredibly stiff. There was a lot of friction, even when freewheeling, and various clunks and creaks were coming from the hub. I checked (so I thought) for any obvious problems, but I couldn't see what might be causing it. I was forced to conclude that my Shimano Nexus 8-speed hub gear was having problems, and needed servicing and perhaps some new parts.
It was difficult to find a cycle shop which had the necessary know-how and tools to service Nexus hub gears, and the nearest I could find would mean transporting my bike by car (particularly as it was difficult to ride with the gear problems). I didn't have time to take it in the week, but on Saturday, Mr. Bsag and I struggled to get the bike in the car. With a very small car and a rather chunky bike, this was never going to be an easy fit, and even after we'd taken the front wheel off, we still couldn't get the hatchback closed. So Mr. Bsag went to take the back wheel off as well, and found something odd: the nuts holding the rear axle to the frame were barely even hand-tight — in fact, they were positively loose. Curious. Even more curious was the fact that the headset nut was also extremely loose, resulting in a lot of play in the front forks. Obviously, I should have checked that everything was properly tightened when I had problems, but it didn't occur to me, as I check my bike fairly regularly for those kinds of things. We tightened everything up properly, and — lo and behold — the bike was back to normal, smooth operation again. That solved the problem of fitting the bike in the car, and the expense of getting it fixed, but left unresolved how it got in that state in the first place.
Now, it's possible that they worked themselves loose, but we'd fixed a puncture only a few weeks ago, and we know that the wheel nuts were fully tightened up then. The problem also came on very suddenly, in the interval between riding my bike to work, leaving it in the bike shed and riding it home. I'm wondering if some mischievous or malevolent person with a spanner has been loosening nuts. They couldn't have got my rear wheel off anyway, because the bike has one of those Continental frame locks which locks the rear wheel to the frame. Whatever the cause, I'll be checking my nuts more regularly from now on. So to speak...