Watts vs lumens

I also have one of those, I had read the stories and took the risk anyway. As you say if they are enough to put you off go for one from either of the above UK sellers. It is a fantastic performing light and I'd buy another, though I'm tempted by the new offerings from the guys mentioned.

I've a couple of the 5W cree ones as well, they are fine for on the lit roads at night but struggle when there are no street lights. I wouldn't think having 4 of them would help either tbh. Good as a commuter but if its offroad riding I'd stick with some a bit more powerful.

At present I commute with two of the torch bar mounted 5w ones supplemented with a helmet light. Sometimes a 1000lumen torch and sometimes the 1400 lumen cree light. Off road I have a 1000 lumen torch on the bars and the 1400 lumen cree on the head. The Cree light also has one of the diffuser lenses, it can be a bit spotty without.

Going back to my original question of how to compare halogen watts to LED lumens, I now see that Lumicycle provide an answer. They still sell the halogen systems and they have an equivalence in the table - they say the 12w spot gives 370 lumens and the 20w flood gives 650.

However as we've already seen courtesy of suburbanreuben, Lumicycle's own photos tell a different story - the 12w spot is as bright as a 600 lumens LED and the 20w flood is brighter than an 850 lumen LED. I think this just goes to show that a lumen count is a very unreliable measure and hence is almost always exaggerated.

When you combine that with the fact that China is a vast unregulated market and trading standards in this country has been cut almost out of existence, you're inevitably going to get hugely exaggerated claims for lumens. But on the other hand, lots of people say 'well it's bloody bright anyway, so who cares if the claims are exaggerated?' You pays your money and you takes a chance.

The issue is also the beam pattern (all this solid angle stuff); at the end of it nothing can be compared and so you are back to the beginning.

The cheaper LEDs also lose brightness very fast - the first generation ones in my kitchen went down to 50% within a few hundred hours.

They get cheaper and cheaper each year. They started out at £50 a few years ago, they were £30 last year and this year you can get them for less than £20. I wonder how they do it without affecting the quality

Looks like a Chinese Cree XML-T6 jobbie in a different casing.

I agree that it looks a bit expensive for what it is, but surely that's the point. Provided the T6 bulb is genuine, they all have the same excellent bulb, but there are huge differences between the different makers - differences in the housings, in the connections, in the batteries, in the battery chargers and in the general design and workmanship. It's all those differences that make the difference between a superb light and an unreliable safety hazard that we have to be wary of, not the bulb itself.

i just got those

http://www.ebay.co.uk/itm/230825016348

only used them once but :

they are half the weight of the Cree I have
more powerfull
much better lense , no white spot in the middle .

and arrived in less than 10 days from china with a uk plug adaptor .

All I was saying is there are lots of cheap XML-T6 (and before that SSC P7) lights with different style casings but the same internals and the same glowing button on the back, and that light appeared to be one of them. I've only seen a few so I don't know how they vary in quality, the Magicshine one appeared to be slightly better in terms of connectors, o-rings gromits etc. but as far as I know still had the same driver, battery, charger etc. issues. I've had a proper look at the one in the link now and it does look like one of the better ones. It has three light levels plus a flash (they normally have two plus flash) so maybe it has a better driver with a proper heat path to the outer casing and as the seller sells high quality battery packs for mountain biking I would imagine the battery pack and charger are higher quality than the ebay lights. That alone would justify the higher price too.

As for the LED I believe they all have genuine Cree XML LEDs. I have one of the £30 ebay ones and despite its poor quality the LED is an definitely a Cree XML.

Well, this has all been very educational, thanks to everyone who has contributed.

One last eyebrow raiser from the mtb batteries site. He may be British, but some of the text on his site reads as though it was written by the manufacturer in China. e.g.:

"Overheating protection function: When the light become too hot at full power, the light will get down to 70% brightness. Usually this will be 8 mins at full power, then turn to be 70% mode..."

OK, overheating protection is fine, but this sounds as though the light can't be run on the high setting for more than a few minutes without overheating and getting tripped down to medium. So it may be a 2,000 lumen light, but only for 8 minutes? In which case, for an evening's riding it's a 1,400 lumen light sold as a 2,000?

That's pretty much the norm for most high powered lights these days, even the ones costing hundreds of pounds. They need cooling air passing over them or they will drop into a lower mode. Its not usually a problem in the winter and you only ususally use the highest mode for fast decents anyway.