Lights: LEDs or incandescents?

[ed_b]

Hi all,

I'm going to fit my winter lights before very long, and was wondering about changing to LED versions.

My understanding is that LED lights consume less power than incandescents.

1) Am I right?
2) If so, is there less drag on the dynamo when the lights are switched on? Obviously with the lights off there would be no difference, but I'm wondering if ?lower ?resistance at the light (I'm not good on physics...) means lower drag at the dynamo.

3) Do LEDs do a good enough job? I love my halogen front light, lights up a country road perfectly. Do LEDs do as good a job? I see some around town that look bright: I can't tell if they're good at lighting the road, or just good at getting car drivers' attention.

Any help much appreciated.

PS, have read the recent thread on Lights recommendations but doesn't compare LEDs with halogens.

[andrew_s]

For the same amount of light, LEDs do use less power than incandescent. However, the available models generally use about the same amount of power, but give a lot more light, without the problem of old bulbs popping or going dim.

The common LED dynamo lights are from Busch & Muller. There are 3 ranges - in Lyt, IQ Fly and Cyo (in ascending order of price/brightness), with various options (basic, standlight, switch, senso, and daytime running lights, in various combinations)
Standlight = light stays lit for a few minutes after you stop (traffic lights, right turns)
Senso = light turns itself on when it's darkish - handy for tunnels, under thick trees, or just to not have to stop.
With a sidewall (bottle) dynamo, only basic or standlight are useful
Using a hub dynamo you always have power available, so the switch, senso and daytime light options become useful

Hub dynamos give lower drag than bottle dynamos, at the expense of a small amount of drag when the lights are off. In practice, you don't notice any drag even when the lights are on. Prices start at about £80 for a wheel, though it can be less if you do your own wheelbuilding.

For battery lights, you get either more light or a longer run time when compared with incandescent.
Another advantage of LED over incandescent is that they gain efficiency (a little bit) rather than lose efficiency (a lot) when run at low power. This means you can have quite a lot more light and a much longer run time, provided that you don't want both at once. You'd use lower power when in street lights, and max power when going down a hill on an unlit country lane.

[mark a.]

Yes, LEDs are the way to go nowadays. They are very bright, use much less power and don't break as easily. Manufacturers are also finally bringing out some lights which have less of the harsh blue light colour to them as many people still prefer the yellower halogens.

You can buy very cheap LEDs chucking out loads of light, but the quality of the optics is still paramount.

Here's a good article on bike lights with lots of beam shots. I don't know how up to date it is (new LEDs are coming out pretty quickly nowadays) but it will still give a good idea.

http://www.peterwhitecycles.com/headlights.asp

If you're using dynamo, I think the default choice on here is one of the B&M lights.

[Steve Kish]

Whilst halogen does give a nice yellow-ish light, you can sharpen this up a bit by over-volting them up to 120%. HID was quite fashionable a couple of years ago but it now looks like LED lights are the future.

You can get ones that give a very high output and these seem to be coming down since the influx of 'Made in China' units (almost all apparently using the SSC P7 semi-conductor), prices seem to be coming down and lumens claims going up.

[Brian73]

LEDs are great, I soldiered on for many happy years with Ever Ready lamps and huge D-Cell batteries though.

Two rears seem to be the best way of being seen, one on the bike one on the rider (most rears come with a clothes clip)

Checkout this place for good deals on lights

http://www.planet-x-bikes.co.uk/c/q/lights

Hub dynamos can freeze solid in cold wet weather. If you try and ride a frozen dynamo it will break.

[stewartpratt]

You would have to be on crack or a dyed-in-the-wool Luddite to buy non-LED lights these days. For the front, look for one with a Cree or P7 LED or similar (mostly around 1W for c. 300 lumens - a halogen bulb would consume about 12W for that output).

[PW]

Hub dynamos can freeze solid in cold wet weather. If you try and ride a frozen dynamo it will break.

+1. It happened to me in the -13C we had last winter.
By the time it thaws out the water/road salt will have trashed the bearings too. If this happens to you don't try to turn the wheel, just take it indoors and warm it up next to a radiator - and if it's a Schmidt DON'T put grease on the skewer! There's a drain hole in the axle which lets the water out.

[ed_b]

Thanks for all this advice, guys. Looks like LEDs are definitely the way to go.

Does anyone know what the effect on the dynamo drag is? If LEDs have lower current requirements, does that make for a less resistance when the dynamo is powering the lights?

Thanks again. Ed

[snibgo]

A modern hub dynamo powering LEDs will take about 6% of your pedalling power. Bottle dynamos will take more (double?). Incandescent bulbs won't take more power, they will just be dimmer.

[PW]

SON28 hub is alleged to drag at the equivalent to a rise of 5'-0" in a mile when switched on. Barely noticeable, at least with 1 headlamp and 1 tail light. Twin heads "might" (just) be detectable to the rider. The smaller SON28/SONDelux has fewer poles, therefore spins longer if you lift the front wheel off the floor, and weighs peanuts. With 1 headlamp you won't notice the light output difference. I've yet to try either with twin headlamps but I'm intending to this autumn when I finish rebuilding the tourer.

[drossall]

I'm not sure what 5% drag means in practical terms though. I'm aware of my bottle dynamo being switched on, but the drag isn't great.

[pherron]

I think the difference in drag will be negligible. Whether there is some theoretical saving I don't know, but I have run bottle dynamos with halogen and with LED and it isn't, for any practical purpose, any different. I now use hub dynamos and the drag is so low anyway that it wouldn't make a difference I could detect.

As already decided, LEDs are the way to go. You won't regret it. I have been amazed by the B&M Cyo lamp - well worth the money. Whether you have bottle or hub dynamo I would very strongly recommend 'standlight' lamps both front and back because having dynamo lights that stay on when you stop is one of the major advances in recent years.

[CREPELLO]

The only thing going against LEDs (and it's significant) is they aren't very good on wet roads. I don't know why, but water covered tarmac soaks up the light like a black hole, so the overall effect is a much dimmer light than on dry roads. Does doubling up compensate?

But there are some LEDs that are much yellower (or perhaps more pink/yellow). I had such a torch, which I compared side by side with a P7 torch. The light was dimmer (though still usuable), but in the rain it was far better than the P7. A shame that these aren't more common. I prefer the warmer light. I promptly lost the torch (only had it a few weeks!).

[AlanD]

Another advantage with going for LED lights is that you no longer have to pack bulky A batteries for spares, it's now AA or AAA, much smaller & lighter

[ed_b]

This is all a great help - thanks a lot everyone. Off to find a B&M Cyo methinks. Cheers again, Ed