Lights

1700lm from 6 x XP-G R5 suggests they're being run at >800mA (how much more depends on how many of the lamp lumens they manage to get out of the front of the housing to their "laboratory"), so 3.25V and 15.6W total lamp power, 4.5h at that is 70Wh. Battery capacity 14.8V x 5.2Ah = 77Wh. So, well done them for achieving a combined efficiency (driver circuit x optical design) of >91%, especially from such a tiny system. Of course, you can have 100% optical efficiency by just surface mounting the LED chips on the front of the housing, but that does mean that not much of your light gets thrown where you want it, as the beam shots show - the dispersion is basically the more or less uniform hemisphere of a bare chip

How does this ^^ compare with the Exposure, Magicshine and Four4th stuff?
Are you saying that although efficient the beam pattern is crapola?

These look a bit easier to mount on the TT bike to me given their offset mount design but I'd like to see their battery pack too.

Cool tute for upgrading a Hope Vision..
http://troutie.com/blog/entry/13

How does this ^^ compare with the Exposure, Magicshine and Four4th stuff?

Hard to say. At first I was surprised that somebody stuck 6 x XP-G R5 emitters in a box and only claimed 1700lm, because the usual marketing BS requires people to use the highest possible drive current and advertise the gross lamp lumens at that, which would be ~2800lm @ 1500mA for that emitter bundle. So, by way of example, I "did the math", which anybody with the Cree datasheets to hand can do, and discovered the claimed combination of output x duration was pushing the bounds of credibility. I'm not up on the current state of driver circuit design, so maybe >90% is achievable, but that does mean that you have to sacrifice beam shaping for utilisation factor (lumens coming out of the lamp housing/bare chip lumens) in order to get the claimed lab measurement, which could be a false economy. I'd rather have an optical system which put 50% of the lamp output exactly where I want it rather than an omnidirectional pattern, since the useful part of a uniform hemispherical output is about 1/2π or 16% for a conical beam with a spread of 65°

The lesson is to take all marketing numbers with a huge pinch of salt. The important measure is how much light falls on the bit of scenery you need to avoid crashing into, and that's a combination of lamp output, thermal design (lamp lumens drop off fast as the junction temperature goes up, so better cooling can make a material difference) and optical design (how the combination of reflectors and lenses directs the omnidirectional lamp output towards where the light is needed)

Runtime is better with many emitters on low settings than a few emitters on high settings, because LEDs are less efficient at high currents, e.g. for XP-G R5
139lm/350mA*3.00V=132lm/W
463lm/1500mA*3.5V=88lm/W
but adding more emitters makes lights expensive and large, so they don't bother to tell you this. For any given emitter & battery, you get about 50% more run time at the same total output by using 3-4 times as many LEDs at ⅓ to ¼ of the current. Using a lower current also makes it easier to keep the junction temperature down, further improving efficiency, as output drops by about 0.25% per degree above 25°C. With lamps being small and light and batteries big and heavy, it may be better (per my earlier post) to add lamp heads rather than increasing the battery size to achieve the desired result.

Thanks for the detailed reply. I did actually read it all! :)

So, the modular designs like the Magicshine or Ayup with dual heads on the same battery might be a better option? It would eliminate the problem I had with the single Maax-D not quite fitting right due to lack of available space. I guess I need to gather all the claimed outputs, run-times and prices together and pick the sweet spot. Or get fed up with it all and buy the first one I google.

I guess I need to gather all the claimed outputs, run-times and prices together

And then look at reviews featuring comparative beam shots, to see how claimed outputs translate into light where you want it. Particularly with the TT bike, something with no cut-off could be really annoying if your eyes are in front of the face of the lamp housing.

le sigh

Just a quick note on exposures, my joystick started playing up THREE weeks ago, I couldn't turn it off & it is still on (albeit the medium beam) - but three weeks continuously & still going strong....wtf?????

My new reelights are quite good but the magnets are rubbing on the light unit as the magnet passes the light . I have emailed reelight and I'm waiting for a reply at the moment. :|

just received a set of smart lunar 15 lights from planet x for the dimly lit commute to and from work, i must say for the price of £12.99 there great, reasonable size/weight and bright for what they cost.

I've been rocking with those eBay hong kong things, the 20 quid 1300 lumen set. Greased up the threads so I feel better about water proofness but all seems very good, impressed with the quality of the light, the brackets quite good, the rear lights good, the rear bracket is a bit meh :/

Really love having a big selection of lights for my bikes, although maybe I have too many - cat eye something or other set, Cree 1300 lumen set, other Cree type 300? Lumen set, btwin set, a halfords mini knog looky likey set, halfords super bright set (x2/3) and a few of those old kryptonite/xenon set type things........hmmmmm, more than than I thought till I started writing that, only really use a few though, most seem really good quality, just want a really good rear light, smart r1 I think :D

Since my lights went with the bike that was knicked (gits) I've been looking for new lights. I really only ride in town/suburbs, so lights are more for my visibility than anything else, I think I've got about £50 to spend on both sets, but can likely get away with going just over for perfection.

Ideally I'd like to be able to buy extra brackets for them, so that I can fit brackets to all our bikes, and ensure that the lights are where they are needed.

I'm liking the idea of fibre flares for rears, mostly for the side visibility, I feel that they are a step up from the Blackburn Mars I was running before.

Does anyone have any suggestions for front lights? I've noticed quite a lot of riders running a pair of fronts, both in blink mode, which seems to stand out quite well. Recomendations would be great!

both in blink mode

That annoys the hell out of me. I'd rather people ran the stronger light on constant with the other on flashing so the pulsing stands out but isn't so extreme. Less annoying as a driver and also means you can see where you're going easier.

What was the verdict on this? I'm contemplating buying one.

Mine has played up twice, once it got stuck in charging mode and wouldn't turn on and once it got stuck on and wouldn't turn off. The shop are replacing it for me.
I'm hoping I was just unlucky with it because I'm loving the brightness of it, far more confident on unlit streets. Traffic seems to be taking more notice of me too.

It is a lot of money to spank on a light but if you have to take on unlit roads regularly I say its worth it. As long as the replacement behaves itself that is!

this turned up today.

I'll give it a grease before taking out in the rain. The casing actually overlaps itself a bit so I'm hoping it will keep the wet out ok.

This has already let in water, couldn't get it to turn off the other day without removing the battery and when I got home tonight I realised it had turned itself off at some point on the way home.

Since my lights went with the bike that was knicked (gits) I've been looking for new lights. I really only ride in town/suburbs, so lights are more for my visibility than anything else, I think I've got about £50 to spend on both sets, but can likely get away with going just over for perfection.

Ideally I'd like to be able to buy extra brackets for them, so that I can fit brackets to all our bikes, and ensure that the lights are where they are needed.

I'm liking the idea of fibre flares for rears, mostly for the side visibility, I feel that they are a step up from the Blackburn Mars I was running before.

Does anyone have any suggestions for front lights? I've noticed quite a lot of riders running a pair of fronts, both in blink mode, which seems to stand out quite well. Recomendations would be great!

Within your £50 budget, I'd recommend the Moon Mask 5.0 front light, and a straight choice from 3 rear lights - RSP Astrum (I have this), Smart Lunar R1, and the Blackburn Mars 4.0 (I have this also).

Moon Mask 5.0 (http://www.jejamescycles.co.uk/moon-mask-50-item172890.html)

RSP Astrum (http://www.rutlandcycling.com/16758/RSP-Astrum-Super-Bright-Rear-Light.html)
Smart Lunar R (http://www.highonbikes.com/smart-lunar-r-1-watt-led-superflash-rear-bike-light-new.html)
Blackburn Mars 4.0 (http://www.parker-international.co.uk/10899/Blackburn-Mars-4-0-Rear-Bike-Light.html)

That annoys the hell out of me. I'd rather people ran the stronger light on constant with the other on flashing so the pulsing stands out but isn't so extreme. Less annoying as a driver and also means you can see where you're going easier.

As this is foremost a cycling forum, my personal sympathies lie with fellow cyclists, and I really am less bothered by the predicament of those riding cosily around in 2 tons of steel.

@MrDrem, I too have 2 headlights on my handlebar. If it is dark, or snowing (none yet so far), or foggy, I use both at the same time; otherwise I just use one, but ensure that my batteries are always well charged.

I've been recommending the Astrum to people that have asked. I think it's a really great little light. You can glue it onto the bracket if you're so inclined and are still able to swap out the batteries.

I'm really pleased with my Moon gem, for it's size it really helps as a flasher.

As this is foremost a cycling forum, my personal sympathies lie with fellow cyclists, and I really am less bothered by the predicament of those riding cosily around in 2 tons of steel.

what a stupid thing to say. if thats the case does that therefore mean that car drivers shouldn't worry about our predicaments and just do what they feel, irrespective of how that impacts on other road users?

http://ecom1.planetbike.com/3034.html

Planet Bike... I'll never buy any other brand again. This one outlived 2 Blackburn Mars 4.0... hardly change the battery and its GOOD.

I know they look like those SMART ones... but they're not. They are sturdy and good.

what a stupid thing to say. if thats the case does that therefore mean that car drivers shouldn't worry about our predicaments and just do what they feel, irrespective of how that impacts on other road users?

I disagree with you. If you had carefully read my words, the one that carried most weight in that context, was the word less.
It did not mean not at all. The word stupid is very easy to use. N'est pas?

As a cyclist who drives a 1200kg car, I have little sympathy for bad cyclist or driver behaviour because I know it's not difficult to get it right.

There are cyclists that drive.

There are drivers that cycle.

There is a huge difference to the thinking and behaviour between the two types. For the main cyclist that happens to drive also, the sympathies lie more with the cyclist's travails. And the opposite appears to be true also. You seem to represent one camp quite clearly.

That annoys the hell out of me. I'd rather people ran the stronger light on constant with the other on flashing so the pulsing stands out but isn't so extreme. Less annoying as a driver and also means you can see where you're going easier.

This is actually a sound theory.

Not because I care anyone else being 'annoyed' by my puny lights (I get blinded by cars all the time) but because the blinky makes you visible and idicates you're a cyclist (so speed can be suitably adjusted, etc) and the constant light is better for allowing others to judge distance to the rider.

I've been doing this during training on front/rear.

I got an Exposure 'Flare' rearlight for my MTB and commute.

Initial impressions weren't favourable - very bright but the lense was a weak push fit against a rubber o ring and let in water on the first wet ride. Took apart and applied a smear of gasket compound. Worked OK for 6 weeks but now not and about to go back.

Some side visibility but mostly very directional which means the seat post mount needs to be at the right angle - for the seatpost on the 3 bikes I've tried it on it points it too low.

Conversely the Exposure Joystick I have is brilliant, a preused Evans ride it bargain it pumps out a huge amount of focussed light, charges easier (PC usb is really useful) and takes the little red eye thing at the back which is really bright.

As this is foremost a cycling forum, my personal sympathies lie with fellow cyclists, and I really am less bothered by the predicament of those riding cosily around in 2 tons of steel.

Erm, it's in our interests as cyclists to stay alive, which does mean listening and understanding the risks to us.

I wish cyclists would drive more... truly. If only to understand how invisible the vast majority of cyclists are.

God, there are so many problems:

• Lack of lighting
  
• Blinky only lighting
  
• Not replacing batteries
  
• Weak lighting (small knogs only)
  
• Highly directional lighting (small lights pointing at the ground or in the air)
  
• No reflective stuff to compensate or help
  
• No side lighting
  
  

It really is no good to blame drivers and declare that as a cycling forum we don't care for the driver's opinion.

Ultimately, we as cyclists need to realise that the best thing we can do is to take responsibility for our own safety.

Which is not to say others shouldn't act responsibly too or aren't responsible for their actions... but is to say that we should be far more aware of when we do things that result in our increasing the danger to ourselves... such as, poor lighting.

Blinky only lighting makes it very very hard to judge direction and speed accurately. It's even hard to correctly judge position now when weather is sub-standard or there are contributing factors (i.e. wet streets at night that reflect a lot of other lights).

Regardless of what laws say, and people think... if you want to be visible in a way that allows other road users to quickly determine that you're there, which way you're going, and how fast you're moving... provide a constant stream of data rather than a few data points... i.e. a constant light and a pulse.