Livre d'Or

More on lights:

Hub dynamos and the other kind (I don't remember what they are called) are different. The latter are cheaper, but as I understand it make the bike a lot harder to ride and wear out the front tyre faster.

If using a dynamo, a rear light with a built-in capacitor (aka a "standlight") is a good thing: it stays on when the bike is stationary, usually for two to four minutes, so long enough for most traffic lights. Front lights can come with this too, but on the grounds that you can see what's in front of you and you aren't moving, it's less important. (Nice to have though.)

It may be a good idea to get some very cheap small battery lights too and stash them somewhere on the bike (taping them to the underside of the saddle is a good option, maybe?) so that if your dynamo stops working you can get home legally. And I personally wouldn't want to be without the battery powered light that is fitted permanently to my rear mudguard, because I'm not going to notice the rear dynamo-powered light not working until I get off the bike. But as previously noted, I'm in London and there are tipper lorries around, so I take visibility fairly seriously (my normal complement of rear lights runs to 5 including the dynamo, plus a spare. Most people think this is excessive. The USB ones get charged as needed, the others are all fairly long-life and get new batteries every three months whether they need it or not, except in summer.)

Knog 'Blinder' USB-chargeable lights are a bit expensive, but attach to the bicycle very quickly and it's easy to angle the front ones down slightly to avoid blinding passing pedestrians. It's easy to put a D-ring lock through them once they're off the bicycle, in such a way that they can't be nicked without the attachment mechanism being destroyed. This also prevents them being lost in the bottom of a backpack or pannier (though attaching them to a strap -- using a carabiner clip or similar -- means you can see it if they accidentally get turned on.)

I am happy to risk having to push the bike home or go back for it the next day if I have a flat tyre but faced with the possibility of having to use a different form of transport for lack of lights, I'd rather have extra lights.