Front light positition

General cycling advice ( NOT technical ! )
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The utility cyclist
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Re: Front light positition

Postby The utility cyclist » 26 Sep 2019, 3:44pm

Sweep wrote:
francovendee wrote:I use a lot of tracks so does a fork mounted light show up the potholes more clearly? I have cycled in the dark without lights for about a mile along a farm track and not seeing the holes was quite dangerous. :oops:

Am always worried by Having anything that might end up in the wheels.
Can someone recommend a good battery light and mount for achieving this, particularly cat eye?
Have been doing some middle of the night descents on country lanes recently and more light might be handy.

you can buy a brake/mudguard mount for a standard light that would fit on a bar I've got one of these
https://www.ebay.co.uk/itm/BBB-BLS-95-U ... SwY7lctG-K

Brucey
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Re: Front light positition

Postby Brucey » 26 Sep 2019, 3:51pm

FWIW any time the viewing point is higher than the lamp, you will get shadows cast by potholes. Obviously you get bigger shadows if the lamp position is lower.

cheers
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PH
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Re: Front light positition

Postby PH » 26 Sep 2019, 3:56pm

Brucey wrote:FWIW any time the viewing point is higher than the lamp, you will get shadows cast by potholes. Obviously you get bigger shadows if the lamp position is lower.

cheers

Which is just one of the reasons why two lights are better than one. I use a fork crown mounted dynamo light plus either handlebar or head mounted secondary.

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Re: Front light positition

Postby mjr » 26 Sep 2019, 4:08pm

Brucey wrote:MJR, a shadow cast at 12 degrees is just annoying; so is the flickering from the shadows of the spokes. If you ride a couple of hours at night it just makes your eyes more tired than they need be if the illumination isn't fairly even.

They're still not complete shadows (a spoke is much thinner than a tyre and closer to the lamp) so flicker is not as dramatic as some sorts (such as the notorious flicking sun through trees), but I basically agree about the spoke shading and suboptimal illumination of the tyre side, especially when turning right, which is part of why I prefer a crown mount.

FWIW cars pull up to and through junctions at ~4mph often; as I said before the exact angle just changes the way in which you are less likely to be seen.

I am pretty sure that doing that speed just pulling up to the junction is not sufficient to cause a serious "constant bearing" hazard - a car would have to be at 4mph for the whole approach and if they start the approach at, say, 7mph then the bike would have to be going faster than most of us would ride past a junction with an approaching car. Sorry to say it feels like clutching at a straw to replace the previous geometry claim and bolster a prejudice arising from some past bad lamp/mount combo.
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Re: Front light positition

Postby Brucey » 26 Sep 2019, 7:15pm

mjr wrote:
FWIW cars pull up to and through junctions at ~4mph often; as I said before the exact angle just changes the way in which you are less likely to be seen.

I am pretty sure that doing that speed just pulling up to the junction is not sufficient to cause a serious "constant bearing" hazard - a car would have to be at 4mph for the whole approach and if they start the approach at, say, 7mph then the bike would have to be going faster than most of us would ride past a junction with an approaching car. Sorry to say it feels like clutching at a straw to replace the previous geometry claim and bolster a prejudice arising from some past bad lamp/mount combo.


it only needs your light not to be very visible whilst the driver of the other vehicle is looking in your direction. That might only be a small fraction of the time they are pulling up to/out of the junction. I've even caught people in cars not looking at all before pulling out in twilight; these folk presumably do the same thing in darkness too (but I can't see them) and they are essentially relying on bright lights appearing in their peripheral vision. These people are idiots obviously but they and others are not always going to see a partially obscured light.

Windscreen pillars are sufficient of a problem to cause exactly this kind of accident (and thick ones can take 'for ever' to get used to); lights that are not properly visible because they are obscured by bike wheels are plenty enough too. Don't take my word for it; upthread Axle Knutt reports that, in hindsight, this may well have been the cause of his accident.

I've spent plenty of time riding motorbikes as well and when you see a vehicle at a side turning it really pays to keep an eye on the driver of that vehicle; in most cases you can tell if they have looked in your direction and/or they have seen you or not. If you can't see their face because it is obscured by the windscreen pillar as they approach the junction (i.e. the constant bearing problem), you are to be concerned. Its a widely known problem amongst experienced motorcyclists and you are just setting yourself up for the same kind of accident if you insist on using a light that is practically invisible from certain angles.

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Re: Front light positition

Postby mjr » 26 Sep 2019, 8:52pm

For the Nth time, a suitable light is not obscured by the wheel. It is wider than the wheel, so shines around it. Just don't use a narrow one or mount it high.

And to be frank, I don't think relying on trying to spot whether a driver has looked your way is a good way to be riding.
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Re: Front light positition

Postby Brucey » 26 Sep 2019, 10:11pm

mjr wrote:For the Nth time, a suitable light is not obscured by the wheel. It is wider than the wheel, so shines around it. Just don't use a narrow one or mount it high.


for the nth time, if there is much of a shadow, the light is being significantly obscured. Its why most folk don't intentionally have stuff in the way of the light. You appear to have double standards; a blinky is a waste of time yet it is OK to block off most of the only front light you have....? It doesn't make sense...

Ask yourself if a light one fifth, one tenth or one twentieth as bright is really an acceptable light or not; I'm guessing 'not' is the answer that most folk will come up with. Ninety nine times out of a hundred (or something) you might be seen even with a light on the fork because the angle is not quite the wrong one. However the hundredth time (or something) your light will be obscured and your remaining glow worm may go unnoticed. You might as well have a light that only works some of the time; it is a complete absurdity to maintain that this doesn't have consequences.

And to be frank, I don't think relying on trying to spot whether a driver has looked your way is a good way to be riding.


its called self preservation; anything you can do that tilts the odds in your favour might be worth doing. Everyone looks out for potholes; I look out for idiots too.

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Re: Front light positition

Postby bogmyrtle » 27 Sep 2019, 8:15am

In wet weather verge edges become churned up and it can be difficult to see where the verge starts. The verge edge is the only reference point on a dark unmarked road so it is important it can be seen.

As well as lighting the road ahead and being visible to oncoming traffic, the light spread needs to achieve this, or alternatively, a second light suitably placed for this purpose.
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Re: Front light positition

Postby pwa » 27 Sep 2019, 8:49am

bogmyrtle wrote:In wet weather verge edges become churned up and it can be difficult to see where the verge starts. The verge edge is the only reference point on a dark unmarked road so it is important it can be seen.

As well as lighting the road ahead and being visible to oncoming traffic, the light spread needs to achieve this, or alternatively, a second light suitably placed for this purpose.


That's right. A modest light on the bars can do the job of getting you seen. It doesn't have to be super bright for that purpose. But the main light for a dark lane should light verge to verge in an uninterrupted spread to help you make out which way the road is going when the edges are hard to make out.

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Re: Front light positition

Postby Brucey » 27 Sep 2019, 11:26am

its worth mentioning that eyes vary, so folk see things very differently in the dark, so a light that is acceptable to some folk might not be to others. When I was younger I did a lot of miles in the dark and at that time I 'made do' with a ~2W tungsten light powered from an old SA hub dynamo. Not ideal but the alternatives were various crappy battery lights or a tyre driven dynamo; modern hub dynamos and white LEDs didn't yet exist. The tyre driven dynamos were more powerful than the dynohub but they were not only noisy and annoying but they also used to fail with monotonous regularity. The battery lights were, for me, a non-starter; they were not only utter rubbish but they also consumed at least a set of batteries every week, in my use.

These days any modern hub dynamo and any LED dynamo front light (costing ~£15 or more) pushes out more light than my old system ever did. But then my eyes have a few more miles on them too. Also, these days I'm more often riding in an urban or extra-urban environment, not so much on near-deserted country roads.

I won't say that I was able to see every pothole on unfamiliar roads with my old system; but then I rode the same roads often enough that I knew where the potholes were, and they could usually be seen and avoided well enough, if you knew roughly where they were and were anticipating them. The biggest issues I had were on damp roads; the road turned almost black and it wasn't easy to see any fault in the road surface.

For a very long time I rode with a crown mount (which took a few goes to get right) and this was low enough to cast shadows from big holes, but not so low that there was a very long shadow cast forwards by the front wheel. If there is such a shadow it puts some people off; 'what about seeing potholes?' they say. Depending on how fast you are going you need to see the potholes several yards ahead if you want to avoid them, so a shadow that extends a couple of yards ahead isn't really a big problem. Because the shadow remains more or less fixed within your field of view, it is not usually a major distraction. Obviously you are best off with black tyre/mudguard at the front if they catch the edge of the beam and are within the field of view.

FWIW the worst accident I had in many dark winter training miles was that I collided with a badger, which was startled and ran out in front of me.

cheers
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Re: Front light positition

Postby rjb » 27 Sep 2019, 11:54am

Brucey wrote:its worth mentioning that eyes vary, so folk see things very differently in the dark, so a light that is acceptable to some folk might not be to others.
FWIW the worst accident I had in many dark winter training miles was that I collided with a badger, which was startled and ran out in front of me.

cheers


I hit what I think was a badger on the way home from work one night. On a slightly downhill section when I would have been doing 30mph +. I recall seeing something in the road but when I looked closer couldn't see anything. I was then launched up into the air. Fortunately I managed to stay upright and eventually stopped. My wrists felt as if I had broken them with the jolt. I turned around and retraced my route expecting to find a dead animal in the road but only heard something large crawling through the undergrowth.
BTW I recall reading recently that a 70 year old only receives 20% of the light to their retina that an 18 year old gets. Explains why you need more light as you age. :wink:
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Re: Front light positition

Postby Brucey » 27 Sep 2019, 12:02pm

'my' badger had been rooting for crab apples up a bank on the left of the road, and I saw it at about the same time as it saw me. Unfortunately it ran for home, which meant leaping off the bank, directly beneath my front wheel more or less. This tipped me off pretty well and bent my front wheel so badly I had to walk several miles home (in stockinged feet, since my cleats would have been worn to nothing by walking that far on them). Hitting the badger was like running into a large lump of wood, or a damp sandbag, more or less.

The badger itself scurried off into the woods, apparently relatively unscathed. I could have sworn it made a kind of muttley-esque 'heh-heh-heh' noise as it did so...

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Re: Front light positition

Postby The utility cyclist » 27 Sep 2019, 5:23pm

if people can't see what they need to see to keep themselves and importantly others safe with whatever light they have fitted then they need to slow down. All this talk about shadows and angles, it comes down to the fact that many people riding bikes, just like those driving motors, go too fast within the conditions/enviroment for their brains to take in what's in front of them to be able to assess and react.

Same with motorists, a brighter light or one that gives a clearer view ahead simply gives more confidence to proceed at a faster pace and indeed sometimes with too much confidence such that you're pushing to the limits (and beyond) of what you can process (never mind any motorist doing their thing) it's usually at this juncture that people have incidents and then look to get another 'better' light to compensate.

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Re: Front light positition

Postby JohnW » 27 Sep 2019, 10:38pm

francovendee wrote:With winter coming we've decided to get ourselves some lights so we're not tied by daylight hours for our rides.

Where is the best place to mount the front light, forks or handlebars?

I last had lights on an old Raleigh that had a mount brazed to the fork. With the bulbs of the time running from a hub dynamo it was just about OK.


I always have two lights, bracketed off the handlebars.
That's my preference, following thought process and experience.
That's just me, not a recommendation to anyone else.

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Re: Front light positition

Postby JohnW » 27 Sep 2019, 10:44pm

[quote="rjb................BTW I recall reading recently that a 70 year old only receives 20% of the light to their retina that an 18 year old gets. Explains why you need more light as you age. :wink:[/quote]
I've been 18 and I've been 70 and I'd question as much as 80% loss.
It does explain why I need better light to read "Cycle" than I did to read the Gazette..................