Re: Highwaycode and pedals question


Matt B wrote:
> >> Probably not as soon as he would have seen the pedal reflectors.
> >
> > Thus indicating a lack of knowledge on the laws of physics.. Ever heard
> > of the inverse square law?
>
> It's no to do with the intensity, but to do with the fact that the pedals
> are moving, that makes the reflected light from them more conspicuous. The
> effect is similar to that of flashing amber lights, like those used to make
> tractors and other slow vehicles more conspicuous.
>
> BTW the inverse square law also applies to the powered lights on a bike ;-)

Very good. Now, as your follow up to show you understand how the
inverse square law applies.

A car light produces 100 units of light per unit area at a distance of
1 m. A bicycle rear light 1 unit.
Taht should be about the right ratio for a 100W car headlamp to a 1W
cycle lamp.

At which distances will the cycle light be brighter than the reflected
light of the headlamps assuming the reflector is 100% efficient.? How
much brighter will the cycle light be than the reflector at 50m?

> >> > What speed
> >> > were they driving to not see this otherwise legally lit cyclist?,
> >>
> >> Does it matter? The sooner they see them the better, and I content that
> >> the
> >> moving amber reflected light is a lot _more_ conspicuous than the other
> >> light sources you mentioned.

> > A reflector is not a light source.
>
> Which is why I referred to the light from the pedals as "reflected light".
> Perhaps you also know that most of the light you see from most vehicle
> lights is also reflected light, the clue being in the name of the component
> inside the light - the "reflector" - that it is reflected off.

Essentially the light is a fixed source. All the light you see is
reflected (apart from looking directly at the point source), that is
how you see things. The point being that if you cannot distinguish the
reflector, with it being too far away to be observed against the
reflected light from the near distance, what use is it moving? Wheras
you will see the rear light much sooner.

> > Once again you are high on
> > supposition and short on any meaningful data (or correspndence with the
> > real world).
>
> An invalid conclusion, being that it is based on a false premise.

No meaningful data has been shown. The premise is not falsified.

>
> >> > and
> >> > why would they expect then to magically be able to see them if they
> >> > have BS 6102/2 pedal reflectors?
> >>
> >> Any advantage is a benefit. If they see/notice the cyclist sooner than
> >> with
> >> only the other lights then there is _more_ time to react. The more time
> >> to
> >> react the happier the outcome is likely to be.
> >
> > That is an if. You haven't demonstrated it to be the case. I would
> > submit, from personal experience and a sound knowledge of the
> > appropriate optics, that a BS6102/3 rear light is visible from *much*
> > further away than reflectors of whatever source.
>
> Visibility is one thing, conspicuity is the key here though. Why do you
> suppose that flashing warning lights flash? Could it be that they are more
> conspicuous than steady lights - perhaps.

And your reference to the time taken to observe a steady as opposed to
moving light is? And it's relevance in terms of time and distance? And
the ease of determining spatial positioning of a moving or flashing
light?

> > So, in teh real world, the pedal reflectors have no actual benefit for
> > an otherwise legally (or comparitively well) lit cyclist.
>
> Unless you you include conspicuity as a benefit maybe not.

You have yet to demonstrate that they aid conspicuity in any meaningful
way. Your data please? or references to studies? Your ignorant [1]
bletherings do not add up to anything without data.

...d

[1] I'll withdraw that comment if you can provide appropriate data.

.