B&M Linetec does it work?

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LancsGirl
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B&M Linetec does it work?

Post by LancsGirl »

I was thinking of getting

https://www.sjscycles.co.uk/lighting/bu ... ear-light/

Then I watched a program about black holes and how they used parallax to calculate the distance to Cygnus X-1 https://en.wikipedia.org/wiki/Cygnus_X-1. Which might be a bit the same as working out the distance to a cycle light in front of a driver.

I'm not that bothered about things 6,000 light years away, but on the same principle (sort of[1]), does Linetec just work on the basis of more than one light source arranged horizontally[2]? Or is there some other cleverness about Linetec? They use some fancy-shmancy language - "spatial light" - but is that just advertising puff? If so any wide light should have the same effect, no?

More to the point, has anybody here used one? And how often have cars driven into the back of you? And/or how often have you been pulled into a black hole?

Thanks.

[1] Kinda not the same principle. Maybe stereo vision is a bit like working out the distance to Cygnus X-1, using (in that case) an incredibly long, thin, isosceles triangle. Whereas Linetec works, by implication, by being more than one light source. Whereas Cygnus X-1 is a point. Also it doesn't emit visible light. And there's no cycle lanes there.

[2] I emphasised horizontally because it seems to me that "double" lights should be orientated that way, because eyes are. At least mine are. But I often see "double" rear lights orientated vertically, usually on a seat post.
Jdsk
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Re: B&M Linetec does it work?

Post by Jdsk »

I haven't seen an independent evaluation... yet...

Here's B+M's description:
https://www.bumm.de/en/technologie-deta ... ec-42.html

Image

Jonathan
LancsGirl
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Re: B&M Linetec does it work?

Post by LancsGirl »

Jdsk wrote: 26 Sep 2022, 11:16am I haven't seen an independent evaluation... yet...

Here's B+M's description:
https://www.bumm.de/en/technologie-deta ... ec-42.html

Image

Jonathan
Many thanks. My internet search ability is clearly terrible, apologies for not finding that information for myself.
Jdsk
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Re: B&M Linetec does it work?

Post by Jdsk »

I'd noticed this on and off (!) and it merits discussion. Thanks for raising it.

Jonathan
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interestedcp
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Re: B&M Linetec does it work?

Post by interestedcp »

I own a couple of B&M Toplight LineTec (dynamo version), and have tried riding behind this light and many similar to it.
Yes, I think the concept works very well regarding judging distance, but it also have the advantage of spreading the light so it doesn't bother riders behind you, even though it actually output quite a bit of light.
It is also nice that the dynamo version has a on/off button for the stand light to avoid people saying "Hey you forgot to turn off your light!".
All in all, I think it is a top class rear light. I have no experience with the battery operated version though.
--
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freiston
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Re: B&M Linetec does it work?

Post by freiston »

LancsGirl wrote: 26 Sep 2022, 11:07am More to the point, has anybody here used one? And how often have cars driven into the back of you? And/or how often have you been pulled into a black hole?

Thanks.
I have a B+M dynamo rear light of slightly different design and shape but having "LineTec optics". Being a dynamo rear light, my opportunity to observe it's performance is limited but others have given favourable reports (though as part of a cycling group, not as a motorist gauging distance). Not had any cars drive into the back of me yet but I suspect that this might have been the case with other designs of rear light too. Not been pulled into a black hole either but some associates have queried me being from the same planet [as them].
Disclaimer: Treat what I say with caution and if possible, wait for someone with more knowledge and experience to contribute. ;)
LancsGirl
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Re: B&M Linetec does it work?

Post by LancsGirl »

Related question (maybe).

My current rear light is:

https://road.cc/content/review/21734-rs ... rear-light

I've spent a bit of time carefully engineering a way of mounting it with the two lights orientated horizontally. Whereas it mounts vertically as it comes.

I was working on the principle that two lights should be arranged like eyes.

But maybe I've got that wrong?
LancsGirl
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Re: B&M Linetec does it work?

Post by LancsGirl »

interestedcp wrote: 26 Sep 2022, 11:51am I own a couple of B&M Toplight LineTec (dynamo version), and have tried riding behind this light and many similar to it.
Yes, I think the concept works very well regarding judging distance, but it also have the advantage of spreading the light so it doesn't bother riders behind you, even though it actually output quite a bit of light.
It is also nice that the dynamo version has a on/off button for the stand light to avoid people saying "Hey you forgot to turn off your light!".
All in all, I think it is a top class rear light. I have no experience with the battery operated version though.
Thanks, useful info.

But how do you ride behind your own bike light? Are you sure you've not been pulled into a black hole? On that programme wot I watched, apparently as you get closer to the black hole you see the light from your own spaceship coming back at you. Space-time getting stretched. Or something.
slowster
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Re: B&M Linetec does it work?

Post by slowster »

Image
If anything the above diagram gives a somewhat inadequate impression of how the LineTec lights perform. I have a B&M Toplight Line Plus, and it is very noticeable that light from the fresnel(?) lens also illuminates the much larger reflector below, as the photograph below from B&M's website shows.

Motor vehicle indicator and rear lights similarly use a large plastic lens illuminated by a point light source.

Image
drossall
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Re: B&M Linetec does it work?

Post by drossall »

Surely you can really only judge distance if you know the size of the object at which you are looking? Although anything is probably better than an almost-point source.
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freiston
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Re: B&M Linetec does it work?

Post by freiston »

Depth (distance) perception is a lot more involved than just size comparison, with several cues/processes contributing to the bigger picture. I dare say that there are challenges to depth perception of a single point light source in the dark that a "banded" source would alleviate too. I suspect that our ability to process small and subtle changes/cues could be under-estimated too.

https://www.verywellhealth.com/depth-perception-3421547
Disclaimer: Treat what I say with caution and if possible, wait for someone with more knowledge and experience to contribute. ;)
Jdsk
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Re: B&M Linetec does it work?

Post by Jdsk »

drossall wrote: 26 Sep 2022, 1:30pm Surely you can really only judge distance if you know the size of the object at which you are looking? Although anything is probably better than an almost-point source.
freiston wrote: 26 Sep 2022, 1:48pm Depth (distance) perception is a lot more involved than just size comparison, with several cues/processes contributing to the bigger picture. I dare say that there are challenges to depth perception of a single point light source in the dark that a "banded" source would alleviate too. I suspect that our ability to process small and subtle changes/cues could be under-estimated too.
It sure is. Most analyses of perception now emphasise how the mind generates and tests hypotheses about the perceived world rather than using purely optical methods.

"What could that object be?" "But it isn't moving like that, it must be a... " etc

Jonathan
slowster
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Re: B&M Linetec does it work?

Post by slowster »

It's all relative. A Toplight Line Plus is 90mm x 40mm, which is probably smaller than the illuminated area of a car or motorcyle rear light, but still better than a point light source.

I think that now that there is such a huge difference in the range of lumen outputs of rear LED lights, instead of a uniform output, it is not possible for drivers behind to gauge the distance to a cyclist ahead simply based on a point light source. A high lumen rear light like those made by Exposure and others will be visible so far ahead that I would be concerned that the driver would:

- slow down when they first see the light, believing that the cyclist is only a short distance ahead
- resume their previous speed when they realise that the cyclist is way further ahead than they thought
- fail to slow down soon enough when they do get close to the cyclist.

Something like an 80 lumen light is probably visible from one or even two kilometres. A Toplight Line Plus will probably not be visible from such a distance, but it will be more visible and a better visual cue to an approaching driver at the distances where the driver needs to take action and slow down/prepare to manoeuvre/overtake (check mirror etc.).
Bmblbzzz
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Re: B&M Linetec does it work?

Post by Bmblbzzz »

LancsGirl wrote: 26 Sep 2022, 11:54am Related question (maybe).

My current rear light is:

https://road.cc/content/review/21734-rs ... rear-light

I've spent a bit of time carefully engineering a way of mounting it with the two lights orientated horizontally. Whereas it mounts vertically as it comes.

I was working on the principle that two lights should be arranged like eyes.

But maybe I've got that wrong?
Interesting thought. I have had similar lights in the past but they had to go horizontally due to being mounted on a rack. I'd instinctively think that horizontal is better as it might make you appear wider. Appearing taller would offer no advantage. But in reality I doubt it makes any significant difference from a driver's point of view.
LancsGirl
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Re: B&M Linetec does it work?

Post by LancsGirl »

slowster wrote: 26 Sep 2022, 2:14pm It's all relative. A Toplight Line Plus is 90mm x 40mm, which is probably smaller than the illuminated area of a car or motorcyle rear light, but still better than a point light source.

I think that now that there is such a huge difference in the range of lumen outputs of rear LED lights, instead of a uniform output, it is not possible for drivers behind to gauge the distance to a cyclist ahead simply based on a point light source. A high lumen rear light like those made by Exposure and others will be visible so far ahead that I would be concerned that the driver would:

- slow down when they first see the light, believing that the cyclist is only a short distance ahead
- resume their previous speed when they realise that the cyclist is way further ahead than they thought
- fail to slow down soon enough when they do get close to the cyclist.

Something like an 80 lumen light is probably visible from one or even two kilometres. A Toplight Line Plus will probably not be visible from such a distance, but it will be more visible and a better visual cue to an approaching driver at the distances where the driver needs to take action and slow down/prepare to manoeuvre/overtake (check mirror etc.).
Indeed. Bike lights are a mess. Varying from non-existent, through pathetically weak all the way to dazzling flashing strobe effects visible from space. With a wide variety of placement and duplication. With the consequences you suggest.

Car drivers can, and I have been, stopped for having one bulb out. MOT tests light alignment. I've now seen two opposite sorts of DIY cycle lighting idiocy in my town. Somebody who thought it was a good idea to have a flashing white light on the rear as well as the front of the bike. And the other variant, red lights front and rear. God knows what the riders were hoping to achieve.

It's time to have regulations that make sense, which are known, and which are enforced. As I've said in previous posts, I'm keen to be absolutely "legal", whatever that hell that means. My front light is StVZO, I've got pedal reflectors, and a rear reflector. I think those B&M rear lights are StVZO.

Interesting to note that I "noticed" some pedal reflectors the other day (while driving). I don't know it was because:

1. They're so rare I've not observed them before.

2. I'm an unobservant driver.

3. Now that I've got them I am more sensitive to their existence.

Or a combination of all three.
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