Front lights again

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pwa
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Front lights again

Postby pwa » 29 Jan 2019, 11:30am

I have one of these on its way from Evans.

https://www.evanscycles.com/exposure-st ... n-EV313642

It seemed like a bargain so I thought I'd add it to the family's arsenal of lights. I won't be using it on a high setting, so long run times are the aim, with reasonable lighting.

I will be treating this as an experiment, seeing if I can utilise this light without blinding oncoming traffic but at the same time lighting up the road far enough ahead. The light does have a "dip" function via a remote switch, so that should help. We'll see. I'll report back when I've got it and played around with it. If it turns out to be unsociable on public roads I'll just have a really good camping torch.

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mjr
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Re: Front lights again

Postby mjr » 29 Jan 2019, 1:48pm

If it causes trouble, try measuring the beam angle to work out whether it's even theoretically possible to aim it so the top of the main beam isn't above horizontal without the centre bright spot being too close to the bike?

I saw someone yesterday with a non-dazzling torch-like light... but when I got closer, I realised they'd aimed it almost straight down, which I suspect meant their right arm blocked the bright spot from view and allowed them to see forwards!

I've just bought one of these for use on the winter bike (which currently has no dynamo). Maybe we should compare reviews? https://www.ebay.co.uk/itm/Dansi-StVZO- ... 4047061193

I also bought a little collapsing camping/walking lantern from Mountain Wherehouse (because you always go in and go "Where is it?" because they put the same type of thing in about three places around the shop) for £4 reduced which seems a bit tougher than the plastic one which died a few weeks ago. Why would you want a torch for camping?
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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mjr
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Re: Front lights again

Postby mjr » 29 Jan 2019, 1:49pm

I see that Exposure's a bit different to other similar lights I've seen because it claims a "road specific beam" but if so, why's it not claiming compliance with any standard?
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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Bmblbzzz
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Re: Front lights again

Postby Bmblbzzz » 29 Jan 2019, 2:16pm

I have an Exposure Strada but a much older one. I can't remember how many lumens, might also be 600, but certainly amply bright enough and the beam is definitely shaped: quite wide and flat on top. Beam shape changes a little from "dip" to "high", brightness changes more. But I expect the beam shape is slightly different now, mine has side by side emitors rather than one on top of the other.

As to why it doesn't claim compliance with any specific standard, I expect that's because it doesn't comply with any! It would incur costs but offer no commercial advantage, because there is no enforcement (and if eg BS6102 were enforced in UK, it would probably be too bright to pass) and it's not something buyers look for. That doesn't mean it's not a decent shape, just it doesn't have a certificate.

mjr wrote:I also bought a little collapsing camping/walking lantern from Mountain Wherehouse (because you always go in and go "Where is it?" because they put the same type of thing in about three places around the shop) for £4 reduced which seems a bit tougher than the plastic one which died a few weeks ago. Why would you want a torch for camping?

A headtorch is great for camping. And angle-able one is best, not too bright cos you don't need much light, especially for close things like cooking or searching in the tent for whatever.

pwa
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Re: Front lights again

Postby pwa » 29 Jan 2019, 2:22pm

mjr wrote:I see that Exposure's a bit different to other similar lights I've seen because it claims a "road specific beam" but if so, why's it not claiming compliance with any standard?

It isn't compliant. They are due to release a fully compliant light soon. This, I think, was their now discontinued stab at making something with a more shaped beam, but of course it is going to need responsible use in a way that a fully shaped beam would not. I suspect that I will not be able to use full power on road and that I will have to angle it down more than I would if I had the roads to myself. So downhill speed will be reduced.

It has two LEDs. One produces a rectangle of light, and the other a longer reaching round beam. The remote switch allows you to go from full to dip, and on dip the long range round beam is reduced. I will set it up for long run time so I will not be pumping out the full claimed 600 lumens even on the chosen High setting.

What this all means in practice I don't know, but I will report back. My hunch is that this is a light that can be used responsibly and do a good job if you don't try to get too much light too far down the road. And if it doesn't do that I have just bought a really good torch for use off the bike.

One thing I really like about Exposure is that you can choose from a menu of settings, so that the two (or three if you prefer) settings available on a ride are ones that suit you. For me that usually means choosing a couple of relatively lower powered settings as my High and Low, resulting in huge run times. So I won't be getting 600 lumens.
Last edited by pwa on 29 Jan 2019, 2:46pm, edited 1 time in total.

Bez
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Re: Front lights again

Postby Bez » 29 Jan 2019, 2:41pm

IME, I've simply never managed to get any forward-firing (symmetrical/scattergun beam) emitter to simultaneously (a) get the hot spot far enough down the road for riding at normal speeds in the dark and (b) not dazzle oncoming road users. In most cases I struggle with even one or the other, and I suspect that when you do the maths around the light distribution that actually ends up on your retina when you angle a conical beam up or down, the former is pretty much theoretically impossible.

I tried the original Strada (well, several, I kept finding a fault that Exposure couldn't reproduce) before I gave up and started using dynamo lights, and it still suffered from the same problem. One lens gave a standard circularly symmetrical/scattergun beam and the other used a diffractor to spread the beam horizontally. Still a symmetrical scattergun, it's just elliptical rather than circular and aimed along the same horizontal axis. Not "dipped" as IIRC they (at the time) called it. In fact I bought a Fresnel sheet and cut a circle out of it and stuck it on, to deflect the low beam downwards (otherwise, if you aim the low beam down a bit to reduce the dazzling, when you turn on high beam you've just got a pool of light where you absolutely don't want it… and vice versa). Which worked in so far as it pitched the beams at different angles, but again it couldn't solve the inherent impossibility of trying to get uniform road illumination from a symmetrical beam.

Not sure how much the design has evolved, but £80 seems like a billy bargain in any case. Tempted to get one as an MTB light, I've got two Joysticks which I could probably sell for a similar price.

They did show some StVZO models a while ago:
https://singletrackworld.com/forum/topi ... ad-lights/

They seem to be using a refractor (like the B&M Lyt) rather than a reflector (like most high-end StVZO lights) which is a curious decision at that price point. £385 buys a lot of dynamo kit, along with permanent freedom from battery anxiety :) even if you're not going to come anywhere close to 4000 lumens with a dyno light.

A StVZO-compliant version of the Revo would be a fine thing indeed, but it would probably cost as much as paying a man in a Land Rover to drive behind you with a set of searchlights on.

Caveat: I am quite abnormally fussy about lights…

pwa
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Re: Front lights again

Postby pwa » 29 Jan 2019, 2:57pm

My testing method for angling bike lights is very scientific. I put the light on the bike, point it roughly where I think it will do a good job for me, then I prop the bike up on something and walk down my street to be able to look back at it as if I were oncoming traffic.

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mjr
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Re: Front lights again

Postby mjr » 29 Jan 2019, 3:14pm

Bmblbzzz wrote:As to why it doesn't claim compliance with any specific standard, I expect that's because it doesn't comply with any! It would incur costs but offer no commercial advantage, because there is no enforcement (and if eg BS6102 were enforced in UK, it would probably be too bright to pass) and it's not something buyers look for. That doesn't mean it's not a decent shape, just it doesn't have a certificate.

Indeed, but without a certificate or even a claim, how can you tell what shape it is? I'd even settle for claimed compliance with one of the voluntary rulesets like RKF (which assumes compliance with the basic NL law, so no symmetric beams) or WHS on https://swhs.home.xs4all.nl/fiets/tests ... eersregels

As for "no commercial advantage", there are some cyclists who won't knowingly buy rubbish lights any more and I suspect as more practical cyclists start riding, there will be more who get sick of a sequence of wasted money on bad lights including some quite expensive ones from the likes of Lezyne and Supernova, so there is some commercial advantage. Maybe not enough for the EUR 2500 that I read full StVZO testing costs, but there is some!
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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pwa
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Re: Front lights again

Postby pwa » 29 Jan 2019, 4:09pm

Just to be clear, the Strada in all versions has a symmetrical beam shape, so no cut-off. You can use the lamp upside down if you want to. Being considerate to other road users requires a combination of pointing it down a bit (hopefully not too much) and putting it on Low when anyone is coming the other way. The remote switch helps with that. It has a wide beam, which suits me. I have read, but am yet to confirm, that in Low mode it puts a letterboxy shape down, with reduced spill.

The drawback with StVZO lamps I've seen is uneven lighting on the road. Shadows and bright spots. If Exposure, with their new lights, manage to produce an even pool of light directed exactly where you need it, they will be the first lights I know of to do that. But out of my price range at the moment.

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mjr
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Re: Front lights again

Postby mjr » 29 Jan 2019, 4:29pm

pwa wrote:Just to be clear, the Strada in all versions has a symmetrical beam shape, so no cut-off.

I'll let you and Bmblbzzz figure that out between you, until we have photos.

The drawback with StVZO lamps I've seen is uneven lighting on the road. Shadows and bright spots.

Bright spots, sometimes, but my crivit StVZO lamp is much more even and a wider centre bright area than my very old BS Cateye.

Shadows? I don't understand how that's possible unless there's a severe flaw in or an obstruction on the lens. I'm surprised if StVZO doesn't prohibit such things, but I don't know its details well enough.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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pwa
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Re: Front lights again

Postby pwa » 29 Jan 2019, 4:41pm

mjr wrote:
pwa wrote:Just to be clear, the Strada in all versions has a symmetrical beam shape, so no cut-off.

I'll let you and Bmblbzzz figure that out between you, until we have photos.

The drawback with StVZO lamps I've seen is uneven lighting on the road. Shadows and bright spots.

Bright spots, sometimes, but my crivit StVZO lamp is much more even and a wider centre bright area than my very old BS Cateye.

Shadows? I don't understand how that's possible unless there's a severe flaw in or an obstruction on the lens. I'm surprised if StVZO doesn't prohibit such things, but I don't know its details well enough.

My B&M dynamo light, which other people rate as one of the best, puts a pattern of shapes of varied intensity on the road, not even at all. I can live with it, and the cut-off for upward light is good to have, but I think better must be possible. Maybe Exposure will be the ones to do it, or maybe not. Our choice of lights today is much, much better than it was just a decade ago. But there is still a bit to go.

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mjr
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Re: Front lights again

Postby mjr » 29 Jan 2019, 4:55pm

pwa wrote:My B&M dynamo light, which other people rate as one of the best, puts a pattern of shapes of varied intensity on the road, not even at all. I can live with it, and the cut-off for upward light is good to have, but I think better must be possible. Maybe Exposure will be the ones to do it, or maybe not. Our choice of lights today is much, much better than it was just a decade ago. But there is still a bit to go.

Not having that B&M, I can't speak to that, but you are probably right that better is possible.

There are some good lights and some are better than a decade ago and the internet means we can at least get them more widely, but probably 95% of UK bike light sales are currently legally-insufficient-for-road crap torches and most of the 5% are low-intensity flashing marker lights rather than stuff you can see where you're going with. My 15-20-year-old expensive BS Cateye would still beat most lights sold today.

We seem to have a complete market failure thanks to a mixture of a press that doesn't scrutinise properly, shops that stock no good road lights, no law enforcement and yes, I'm sorry but I'm going to blame them: loads of club cyclists that are apologists and advocates for the MTB lights they use illegally on roads.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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Re: Front lights again

Postby Bez » 29 Jan 2019, 4:56pm

What the StVZO compliant lights achieve is evenness in perceived brightness across the road surface, which means the further ahead you illuminate the more you send there. Here's what the beam of my Luxos U beam looks like when shone on a vertical surface. As you can see, it's sending the vast majority of its photons to the patch of road just below the horizon, and it falls off markedly below that.

Image

And here's the beam of the Strada 600, taken from Road.cc's review. It's (unsurprisingly) barely distinguishable from a bog standard circular reflector.

Image

When you project those beams from a shallow angle onto a horizontal plane instead of a vertical one it's obviously a very different story: the Luxos gives much more even illumination in terms of depth. The light is mostly sent along the angles where it has to travel furthest (and thus scatter/fall-off most) between the emitter and your retina.

The Strada sends as much light above its hotspot as it does below; and of course, you'd ideally want that hotspot to end up just a whisker below the horizon if you were going to have a fighting chance of even perceived (received) illumination. So you have a choice: aim it straight into people's eyes or end up with a crap distribution of light on the road. Which means, in reality, both.

The Luxos beam does have more artifacts, though, and I assume the reason is that for any given manufacturing tolerance it's relatively easy to make an accurate parabolic (scattergun) reflector and relatively hard to make the more complex reflectors of the Luxos etc. Plus, perhaps even more importantly, the Strada etc use forward-firing emitters, which will distribute unreflected light evenly, whereas the Luxos etc are rear-firing, meaning all of the emitted light is controlled by the reflector.

pwa
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Re: Front lights again

Postby pwa » 29 Jan 2019, 5:29pm

When you google Strada 600 beam shape what you get is images of the light on full beam, not on the "dipped" mode. Even Exposure do not recommend you use the full beam in the face of oncoming traffic.

My Cyo Premium dynamo light is a good light and it does its job okay, but it does put stripes on the road. It doesn't give a seamless pool of light. I give it seven or eight out of ten.

Frustratingly, photos of beam patterns don't usually show you exactly what you will see on the road when you use the light.

pwa
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Re: Front lights again

Postby pwa » 29 Jan 2019, 5:58pm

In reality I rarely use one light on its own, so I try to find two lights that complement each other. If I can combine the Strada 600 on a low power setting with another light on a low power setting I may well get something like ideal coverage. It may even combine well with the Cyo. I use two lights on the front and two on the back in case a light fails. It rarely happens but you never know.