Exposure Revo Mk1 light - any experience?

[Rob Archer]

Spa cycles have got a deal on for an Exposure Hub Dynamo + Revo Mk1 light + wheel build for £295 http://www.spacycles.co.uk/products.php ... 0s170p2793 It looks like a good deal. Anyone got any experience of these dynamos or lights. I've read Chris Juden's review in 'Cycle' but it doesn't cover the Revo light.

Rob

[The Computer Monkey]

You may think I'm biased but I have one and think it's great. Possibly 'overkill' for the road to be honest and you have to point it down so as not to blind motorists but lights up unlit country roads brilliantly.

[Rob Archer]

Thanks. I have a 13 mile commute, most of it on country lanes. Until now I've been getting the train when it's dark, but I'm itching for a ride when I finish work! I love night riding but get seriously fed up of drivers not dipping their lights for a cyclist and reckon the something seriously bright (even pointed down) might make them think sooner - as well as allow me to see the increasing number of deep potholes before they find me.

[stewartpratt]

I love night riding but get seriously fed up of drivers not dipping their lights for a cyclist and reckon the something seriously bright (even pointed down) might make them think sooner

IME motorists dip their lights much, much better when faced with a road-friendly (German) beam, and again IME some will actively put main beam on when faced with a symmetrical beam (even a much lower-powered one than the Revo). This was the whole reason I ended up with a German light: I was fed up with being main-beamed - when using an Exposure light, as it happens - and it's completely solved the problem for me.

The Revo is a symmetrical beam that's really intended for off-road. I have no doubt that it's a really excellent light and will be the brightest dyno lamp you can get. But it's not going to help when it comes to being main-beamed by cars.

[Maelgwyn]

Just found this forum thread - I am seriously considering buying the Exposure Revo, and will report back if I do.

I have had exactly the opposite experience to stewartpratt. I have a 17-mile cycle commute home from work on an evening, which includes 14 miles of pitch black small country lanes.

For some years I had been using cheap Chinese Cree LED front lights with separate Li-ion batteries on my tourer (bought from eBay), which were a huge step up from the old quartz-halogen (QH) SLA-powered lights I used to use. I found that with about 900 lumens I could see comfortably ahead to avoid any potholes at 15-20mph, and the peripheral of the (symmetrical Gaussian profile) beam give me context from the verge and hedge to avoid nausea from 'tunnel-vision' and 'ground-rush' - which I used to get with the narrow QH pencil beam. Furthermore, there was enough light down the road to warn cars I was there, and for them to dip their beam before they came around the bend at 60mph. The authority these lights give you as a cyclist in the face of other road users with double HID beams, such as BMW 4x4s, is the biggest advantage I found, and is a huge boost to my safety as a cyclist. I later bought a 5000 lumen light and found that motorist slowed down for me on narrow sections of the lanes. Aware that I can dazzle motorists, I always shield the upper part of the beam from them with my glove, as they approach - unless they failed to dip, in which case I give them the whole beam!

Recently, when I started getting problems with the cheap Li-ion batteries not having enough charge life, I decided to try a dynamo system for the first time. I had a Shimano 6V 3W dynamo built into the front wheel and used it to power a Herrmann H-One S - at 95 lumens it is one of the highest power dynamo light that conforms to German Road regulations, and is considerably more powerful than most B+W lights I have seen. Even so, I found it quite inadequate for the task of my commute: NO cars dipped for me (I had to give them a blast of my 5000 lumen Cree LED, which I had standing by, to force them to dip!), furthermore I found it hard to see smaller potholes and manure piles on the road in time to avoid them, and found the whole experience harrowing, with just a narrow cone of German Regulation beam pattern lit in front of me.

Now, maybe my ageing eyes (at 55) aren't as good as some of you youngsters, and maybe you don't suffer from the kind of travel sickness (eg: 'ground rush') that I sometimes do; but I reckon that 800 lumens is about the minimum power I require to cycle comfortably and safely on dark UK country lanes. I was therefore pleased to find that Exposure had released such a dynamo light as the Revo (albeit somewhat expensive); and equally pleased that it violates German Road regulations, which I belief discriminate against the safety of cyclists!

[stewartpratt]

Worth noting that the H-One S is not 95 lumens, it's 95 lux. A completely different measurement. Also its beam is very narrow compared to the latest lights like the Cyo Premium.

Odd that your experience differs so wildly: mine went from being main-beamed on every ride with my Exposure light, to never having been main-beamed once since I've used a variety of B&M lights, which have been fine for me visibility-wise to at least 30mph. I certainly wouldn't want to be having to shield the light with my hand whilst riding whenever a car approaches

[Maelgwyn]

I will have to look again at the spec of the H-One, because lux doesn't make sense as an overall measure of a light's output because it is only an 'instantaneous' radiance measure over a infinitesimal angle or area - equivalent to Watts per steradian or Watts per square meter - and needs to be integrated up to lumens to give a usable measure of a light's output. I plan to purchase a good lux meter, so that my son and I can integrate the true lumens of all these lights, and compare them with the manufacturers claims.

Everyone's experience can differ according to their eye sensitivity (different from acuity - I don't need glasses) and their tolerance of road imperfection, risk of animals running out from the verge etc. Maybe country drivers on the Fylde (North Lancashire) in their big 4x4s or Subaru Imprezzas etc, behave differently from where you cycle. I definitely experienced less respect when I rode home without my Cree LEDs, with only the H-One - and this was an objective measure (eg: number of cars that dipped for me, how fast and how close they passed me on the lanes). I find putting my hand over the top half of the light lens to be a convenient compromise, until some enterprising manufacturer comes out with a powerful bike light with a dip/main beam option - my light is right in front of my face, on my 'Space Bar' above the handlebars, so is easily reached.

BTW: I've never done anything like 30mph on my bike at night! My commute is generally flat, and I have only done that kind of speed on day tours In the hills

[stewartpratt]

I will have to look again at the spec of the H-One, because lux doesn't make sense as an overall measure of a light's output … and needs to be integrated up to lumens to give a usable measure of a light's output.

Depends on how you define "sense" and "usable"

The lumens tell you how many photons the thing vomits out; the lux tells you how brightly it illuminates a certain area. Neither tell the whole story, of course: two German beams with the same lux might be totally different in width, whilst two torch-style beams with the same lumens might produce either a bright hotspot or a milder flood. And then there are beam artifacts to consider, regardless of output. But a German beam will never need to output as many lumens as a torch-style beam, since it's not throwing half of the light into the sky.

[Maelgwyn]

I agree that neither a single lux value nor a single lumen value tells the whole story of a light's useful 'power', and much depends on the beam pattern; however a single lumen value of the whole beam is far more useful than than a single lux value of some tiny part of the beam pattern (usually chosen by the manufacturer to make their product look good).

I also don't agree that light projected above the horizontal is of no use on a bike light on the road (as German BMW-driving lawmakers seem to think) - as with car long-distance driving lights, I find that lighting up the hedges, road signs, trees etc to be useful context for comfortably riding a dark lane at night - even more so if decending a hill. And most German dynamo lights I have looked at (eg: B+M) are so puny that half a Cree light pattern is still 10 times better than them! If USE can make the Revo put out 800 lumens, why can't B+W make a car-like dipped pattern (that conforms to German Road Regulations) that is 800 lumens?

My benchmark for a good bicycle front light is that: (a) it should be comparable to small family car headlamps - so you get noticed/respected, and (b) it lights ALL the road ahead (including the verge) out to about 50 metres to near daylight illumination - for comfortable and stress-free riding. I cycle commute 2 or 3 weekdays in the Winter (depending on weather and family commitments - more in the Summer), and I treat each night ride as an adventure. If I was to make it an ordeal by trying to manage on inadequate lighting, then I would just drive to work in my Forester (which has ~8000 lumens of beam! ), and leave cycle commuting for the Summer (as most of my cycling colleagues do).

Just my opinion, Stuart

[Bicycler]

If USE can make the Revo put out 800 lumens, why can't B+W make a car-like dipped pattern (that conforms to German Road Regulations) that is 800 lumens?

Luminance. If you want a bike light several times smaller than a car lamp then the amount of light emitted must be reduced massively or it will dazzle. Car lamps also dip to the left.

[RickH]

Odd that your experience differs so wildly: mine went from being main-beamed on every ride with my Exposure light, to never having been main-beamed once since I've used a variety of B&M lights, which have been fine for me visibility-wise to at least 30mph. I certainly wouldn't want to be having to shield the light with my hand whilst riding whenever a car approaches

I found that things improved when I got a Mk1 Joystick and got still better when I got a Mk1 Toro (700 lumen) - I went from frequent staying-on-full-beam from oncoming traffic on unlit roads pre-Joystick to almost none with the Toro, even if I forget to put it down to lower power. In fact recently I got a non-dipper for the first time in a ages - I was going uphill on low power in a lit area & didn't really need any brighter at around 10-12mph when the streetlights stopped. A car coming the other way didn't dip so I flipped to full power & they promptly dipped, I then knocked the power back down to mid power (I notice in passing that newer ones can be programmed to have only 2 power settings rather than having to cycle through a mid power one).

Rick.

[mjr]

I agree that neither a single lux value nor a single lumen value tells the whole story of a light's useful 'power', and much depends on the beam pattern; however a single lumen value of the whole beam is far more useful than than a single lux value of some tiny part of the beam pattern (usually chosen by the manufacturer to make their product look good).

I disagree and manufacturers don't chose because the lux value measurement location is specified in the German standards. I think it's on the floor 10m ahead of the bike but http://swhs.home.xs4all.nl/fiets/tests/ ... ex_en.html probably says exactly. Measuring lumens is far more open to abuse.

And most German dynamo lights I have looked at (eg: B+M) are so puny that half a Cree light pattern is still 10 times better than them! If USE can make the Revo put out 800 lumens, why can't B+W make a car-like dipped pattern (that conforms to German Road Regulations) that is 800 lumens?

They probably could but it would be large, power-hungry and unnecessary. I don't know how old the lights you've been looking at were, but the usually-reliable Dave McCraw rates B+M's Cyo above a 900-lumen torch at http://mccraw.co.uk/iq-cyo-dynamo-headlight-review/

My benchmark for a good bicycle front light is that: (a) it should be comparable to small family car headlamps - so you get noticed/respected, and (b) it lights ALL the road ahead (including the verge) out to about 50 metres to near daylight illumination - for comfortable and stress-free riding. [...]

30mph is 13.4 metres/second, so 50 metres would be almost 4 seconds ahead... and that's for near-daylight not merely good-enough-to-see, which would presumably be even further ahead. How slow are your reactions?

Ah well. I remember grubbing along the verge with an EverReady Frontguard, so maybe I'm easily pleased now.

[edocaster]

£295 seems a bit excessive, even if the wheel is included. I had a stab at building an MTB dynamo light, with the results here: viewtopic.php?f=5&t=82493&p=820630#p820630 - I'd estimate it at over 700 lumens, with the advantage of a high and a low mode, as well as an off switch (why oh why would Exposure go the whole hog of selling a complete system but leave out an off switch???). I've taken it out in pitch black unpaved conditions and it has done fab (I'll see if I can get a video up) in anything but a complete standstill. Cost of build was under £40.

For road use? Usable. But it is slight overkill and won't be geared for throw.

If USE can make the Revo put out 800 lumens, why can't B+W make a car-like dipped pattern (that conforms to German Road Regulations) that is 800 lumens?

Luminance. If you want a bike light several times smaller than a car lamp then the amount of light emitted must be reduced massively or it will dazzle. Car lamps also dip to the left.

A smaller light source may register higher on the glare index, but that's not relevant for the purposes of the German regs. The size of the light may affect the ability of the lens/reflector to tightly shape the beam, but car bulbs and LEDs are in different size ranges, so LEDs don't need a huge reflector. For a tightly shaped beam, what they do need is a reflector/lens that is large enough for the LED die - high-powered Cree XM-L LEDs are 5x5mm, so need a slightly larger optic than a smaller LED like, say a Cree XP-E (3.45x3.45mm). But they certainly don't need a car headlamp-size optic.

I suspect the real reason is B&M don't want to enter a lumen war. What you can get out of a dynamo is amazing, but will hit an upper limit at sensible speeds. Once you reach that point, you're waiting for LED manufacturers to make more efficient chips, while battery lights can rely on increasing input power. Far better to play around with focusing one part of the beam and progressively increasing the lux figures over the product range.

[oldstrath]

I agree that neither a single lux value nor a single lumen value tells the whole story of a light's useful 'power', and much depends on the beam pattern; however a single lumen value of the whole beam is far more useful than than a single lux value of some tiny part of the beam pattern (usually chosen by the manufacturer to make their product look good).

I disagree and manufacturers don't chose because the lux value measurement location is specified in the German standards. I think it's on the floor 10m ahead of the bike but http://swhs.home.xs4all.nl/fiets/tests/ ... ex_en.html probably says exactly. Measuring lumens is far more open to abuse.

And most German dynamo lights I have looked at (eg: B+M) are so puny that half a Cree light pattern is still 10 times better than them! If USE can make the Revo put out 800 lumens, why can't B+W make a car-like dipped pattern (that conforms to German Road Regulations) that is 800 lumens?

They probably could but it would be large, power-hungry and unnecessary. I don't know how old the lights you've been looking at were, but the usually-reliable Dave McCraw rates B+M's Cyo above a 900-lumen torch at http://mccraw.co.uk/iq-cyo-dynamo-headlight-review/

My benchmark for a good bicycle front light is that: (a) it should be comparable to small family car headlamps - so you get noticed/respected, and (b) it lights ALL the road ahead (including the verge) out to about 50 metres to near daylight illumination - for comfortable and stress-free riding. [...]

30mph is 13.4 metres/second, so 50 metres would be almost 4 seconds ahead... and that's for near-daylight not merely good-enough-to-see, which would presumably be even further ahead. How slow are your reactions?

Ah well. I remember grubbing along the verge with an EverReady Frontguard, so maybe I'm easily pleased now.

I think the issue is not just how far can you see, but also the important one of seeing all of the context, not just a narrow strip of road. Enthusiasts for STVZO like to say that all the light goes where it's needed, but frankly this is twaddle - the over optimised beam patterns make road signs, turnoffs and stray deer essentially invisible.

Your comment about manufacturers not picking the distance is accurate, but also I think misses the point. Since they know what distance is used it's simply a question of optimising the beam pattern to put a good number there - the result may look good on paper, but in practice the Revo, or even a DX cheapie, is far more usable.

[tatanab]

Enthusiasts for STVZO like to say that all the light goes where it's needed, but frankly this is twaddle - the over optimised beam patterns make road signs, turnoffs and stray deer essentially invisible.

I disagree. I use Philips dynamo (60 Lux) and battery (40/80 lux) lights with a German cut off beam. They are set to the STVZO standard of how far the beam has dropped at a defined distance. This is still enough for brisk riding in pitch black lanes and the elements of the light (I cannot recall the correct term) that escape upwards are enough that a reflective road sign is clearly visible at 50 yards or more. The place I find the cut off a problem is fast descents with a bend at the bottom. Because there is the cut off, I do not have enough light leaking upwards to illuminate the exit of the bend. So I have to slow down on those occasions. In narrow lanes I have had motorists slow or stop as I approach, and everywhere I ride I find that motorists are more willing to dip and usually at a greater distance as well. The cut off has my vote.