I made a tail lamp using a 10W helmet light. The helmet mounting strap slides onto the velcro on the left side of my rear rack trunk. The NiMH battery fits in the outer pocket of the pack. Initially I used a piece of the rear light repair tape, but I found a 1.5 inch reflector sold to be a reflector hanging from a dog's collar. The reflector pops off the tag easily to give a very nice lens. It is very bright, easily seen in daylight. I've used it in temperatures down to 10 degrees F. I've used it in sleet, snow, and freezing rain. The battery is good for at least 2 hours.
[Edited by Jean Beetham Smith on Feb 20th at 08:07 PM]
I had a taillamp fall off on a recent ride... It was a Vetta 3-LED flasher that I'd had for ages. The mounting fatigued and broke. I found it the next day, run over, destroyed.
So... I stopped at my LBS and bought a recemmended-by-the-shop-owner light, a Trek Xenon strobe. I was skeptical... it was rather small, and lacked the never-fail quality of LEDs...
BUT! This light is B R I G H T ! Bon sang, stare at it and risk damage to your vision! I'm not joking... If your LBS sells Trek bikes and accessories, (The General Motors of the velo)drop in and have the folks there give you a demo.
I think it was US $15.
PS, I usually run two headlamps and two taillamps... One headlamp lights the road 4 to 8 meters ahead, so I can see, the other lamp is aimed into oncoming traffic... so that I may be seen. Plus, if one fails, I can swap them on their mounts and continue on my merry way. Out back, I run one multi-LED flasher on the bike rack, and one strobe light, higher up... I sew a strip of nylon strap fabric to my backpacks, onto which I can clip a taillight.
Vistalite 5-LED, seat-post mount
I've had two of these, and they both worked fine in the solid-on configuration, but when set to flash they worked inconsistantly. Typically, they would barely flash, and by tapping on the unit, it would change. Given that I would encounter numerous bumps while riding, I've never felt confident leaving them at this setting, so I use the solid-on setting.
The best I have had so far (really) is a small $3.00 LED from Wal-Mart. It's made in China (wha?) and comes with two AAA batteries. First sold by Ray-O-Vac, then Team Products, and who knows who next, these are cheap and very bright. Hard to believe.
I always use rechargeable alkalines in them and keep them charged up. This keeps the brightness up. So far, my experience with rechargeables (NiCd are my oldest, Radio Shack, size C), is awesome. My first set still works like new after years of recharging almost daily.