Bike update

When I collected my bike yesterday, I asked if I'd achieved a reasonable mileage for such an amount of replacement being carried out. The mechanic replied that I should bring in my chain after six months so they can test whether it's stretched; if they replace it when it's half-stretched, it won't need the gear cassette and the range wheel replacing too.

I wish previous mechanics had told me this, when I'd brought my bike in in the same circumstances, rather than just "when the chain is stretched and at the end of its life, the gear cassette will need replacing too"; it could have saved me a lot of money.

Mind you, it's possibly in the fine print of my bike manual, which I've never properly read and memorised...

Staving off the SAD: How much light is required?

As regular readers will know, I've been getting up early in winter for the last (crikey!) eight years now so I can cycle to and from work in the daylight and stave off SAD.

The first year I stopped doing it after the midwinter break (i.e. Limmud), as I couldn't be bothered to restart. After about three weeks, I found myself getting depressed, not for no reason, but not for any reason that hadn't been there beforehand. I decided to resume getting up early and see if it would have any effect. I thought my depression might lift after a few days, but, much to my surprise, it vanished overnight.

Last Tuesday evening I found myself getting depressed. I'd cycled to and from work and the start and end of the day so far that week, but on three of those occasions it was heavily overcast and the light levels were low. On Tuesday afternoon, it cleared up, but I only got ten minutes' cycling home done before sunset (due to spending half an hour waiting to meet someone who had forgotten to put the appointment in her diary, and was working from home that day, grrr!). On Wednesday it was forecast to be bright and sunny, so I made the effort to cycle a third day running, which I don't normally do, and lo and behold again my mood lifted immediately.

Later that week, I was talking about this with Giles, who orks my cattle, and he made some assertions, following (as I discovered when I later asked him) both recently reading an article, and talking with a doctor, on the subject, that the Wikipedia page for SAD does not mention, but which bear out my observations and hypotheses, to wit:

• It doesn't take much bright light to do the job. (He said ten minutes; I think, from Tuesday evening a week ago, it must be a bit more, but perhaps not much: I don't get more than fifteen minutes exposure to light on a Tube journey to work.)
• Every time you stop being exposed to bright light, your mood starts declining. This is why commuting to work in full daylight but home in full darkness would still leave me down in the evenings, but commuting both ways before/after the light has quite achieved full intensity does not.
• Clear blue skies and even sunlight through windows has no effect. This might partly be due to the window tinting in my office, but I suspect is more because windows filter out UV-A (the frequencies that tan you)... though not, as I recall rysmiel wryly telling me, UV-B, the frequencies that give you sunburn.

This is why I really wanted to cycle on Tuesday; after my conversation with Giles on the subject, I decided to go and work on the balcony at work for a bit (alternate link for anyone without permission to follow the first one), despite the cold.

I think I might end up doing this a bit more during the winter, at least whilst the weather is warm enough to type outside with bare fingers, if the only good light is during the middle of the day—or it's too difficult to try and make the time up given that I have to leave early at present to catch the sunset.