People might think that carbon soot is the greatest advance in recent cycling technology but I would argue it is the humble LED.
Gone are the days of oil lamps, tungsten bulbs that occasionally made contact with dying batteries the size of half a house brick and of bottle dynamos losing contact in the wet. The LED gives light, and lots of it for the price of very little power. For years cyclists forked out wads of cash for this step jump in effective and reliable lighting despite the silly law prohibiting the use of anything that didn’t carry a BSI kitemark no matter how superior it was.
Now LED is the norm. Poundland are doing rear and front lights for … a pound each! They have got incredibly cheap over the past couple of years. Folks on Colnagos in Raphaware would never stoop below a couple of these Hope monsters @ £70 each:
Those of us of more modest means or wishing to leave our bikes unattended for more than a nanosecond might prefer the 7DayShop variant (top of page) and here: http://www.7dayshop.com/7dayshop-bike-light-hand-torch-ultra-high-power-3w-led-flashlight-with-mount-blue-ring. Just £3.99 and beloved of many of the Friday Night Ride brigade. It includes the handy mounting that fits the handlebars just right. You can afford to have two and one for the saddle bag. I run mine off 3xAAA rechargeables which may not last for ever but carrying an extra three takes no space at all and gets you through a night ride. They have full on, half on and flickering modes. You can’t go wrong unless you want to take out one of these …