LEDs have revolutionised cycle lighting for the serious night-rider.
They are bright (when used in clusters), a good red colour, and many times more reliable than traditional bulbs.
Battery drain is very small, so the light that goes on at dusk can be relied upon to still be good and bright at dawn.
Most important, they are highly directional. This has two advantages for the serious night-rider:
They are very visible from a long way away on the open road, maybe as much as a mile away.
And if a group are riding together, following riders are not dazzled by the LEDs, because they are viewing them off-axis and so see only a relatively dim light.
So to the golden rule when using LED lights - they MUST be firmly mounted so that they point straight along the road - parallel with the road in both vertical and horizontal planes.
Recent commercial designs of LED light are very good with excellent build quality and useful modes, so there is really very little point in building your own. However it is still possible for the do-it-yourselfer to build a back light which is much brighter than any commercial one. The components are these -
Or look in the catalogues for the latest, brightest 10mm clear red LED - they're getting brighter all the time, though some are too directional to be of much use.
The 'brightness' is the manufacturer's spec., and can be taken with a pinch of salt. The diffuse LEDs are remarkably effective, and with fresh batteries can be easily bright enough to upset following cyclists. If you often ride at night in a group, then it would be kinder to build a more directional 2 + 2 configuration instead of the 1+ 3 that I describe here.
Use superglue to mount the three diffuse LEDs in a triangle about 25mm apart, then mount the clear one in the centre. Connect them in series and run them off a PP3 battery (the 9V type that is about half the size of a matchbox).
No other circuitry is required.
Using an alkaline battery, useful life is about 60 hours. A good box for the whole project is Maplin Verobox LL12N, about 70mm x 50 x 25 - but a slightly smaller box would be even better.
Lights of this design have been used by many British riders in the last two Paris Brest Paris rides ('91 and '95), which includes three or maybe four long nights of riding. Assuming you want a rear light that is as bright as possible they will outperform any commercial offering in steady mode. The bare LEDs look a bit weird, but if you've got the best technology, why not flaunt it?
For maximum visibility at the front the mode of modern commercial LED lights is really useful. So, for the best front LED light -
Buy a good commercial light such as the KnightLite 5-LED front light.
Buy 5 x the best bright clear yellow 5mm LED available. Currently a good choice is Toshiba TLYH180P, brightness 12 cd, price under £1.00 each from Farnell, stock code 623-738.
Disassemble the light and carefully substitute the new LEDs for the old. It shouldn't take more than an hour. The green LEDs originally fitted have a specified brightness of around 0.3cd, so the new ones, on paper at least, are over 30 times brighter.
Battery life is much the same - the increased brightness is achieved by improved efficiency and greater directionality.
The legality of LED and flashing lights is a very 'live' issue, which this page is ignoring for now. Assuming the primary purpose of cycle lighting is to attract the attention of other road users, then LED lights are the best ones for the job. LEDs and the Law.
