From: MrMoped on 9 Feb 2007 02:26
"Knobdoodle" <knobdoodle(a)hotmail.com> wrote in message
> "MrMoped" <MrMoped49(a)hotmail.com> wrote:
>> Simple physics really! When switched on, the headlamp assembly pushes the
>> light beams forward (this is particularly noticable in the absence of
>> daylight), this is called an action. So using Newtons third law which
>> states that for every action there must be an equal and opposite
>> reaction, the same force applied by the headlamp to push the light beams
>> is then also applied to the vehicle, pushing it back! Extra petrol is
>> used to overcome the force applied by the headlamps.
> But you've got red ones pushing you from behind and EVERYONE knows red
> ones are faster!
True, as a general rule the red ones are faster and this has been a concern
to (most) motorcycle manufacturers worldwide.
Having a fast red light at the rear of the motorcycle was a huge concern in
the early days of motorcycling as it was soon realised that having a fast
light (red) at the rear and a not-so-fast light at the front led to the rear
of the motorcycle trying to overtake the front at every opportuity - this
was deemed to be "not rider friendly".
To counteract the power of the red light, a very mild or low wattage light
was fitted to the rear whilst a stronger/higher wattage light was fitted to
the front. This has worked very well.
The ratio between front and rear light is very sensitive. A typical setup of
60/55 watt high/low beam front light to 5 watt tail light works well in most
situations but the addition of a 20 watt brake light has added an element of
danger by making the motorcycle unstable. If you require proof of tis, try
- ride along (at any speed) with the mind in neutral and then apply the
front brake as hard as you possibly can and do not ease off under any
circumstances. The rear of the motorcycle will rise and continue rising
until the red, rear light has overtaken the front. Some will try and
attribute this phenomenon to the action of the brakes but that is not 100%
correct. Squeezing the front brake as hard as you can imparts maximum energy
to the faster red light. A similar effect can be achieved by applying
maximum force to the rear brake.
So yes the red lights are the fastest but they can be tamed with some
(un)sound engineering practices so as not to detract from the motorcycling
From: G-S on 9 Feb 2007 02:27
> G-S wrote:
>> Nev.. wrote:
>>> GB wrote:
>>>> "Nev.." <idiot(a)mindless.com> wrote in
>>>>> And you very neatly ignored the bit where I also found that it did not
>>>>> affect the fuel flow and therefore did not use any more fuel... no
>>>>> wait.. you poo-poo'd that because it didn't suit your argument. BZZT.
>>>> I didn't ignore it at all. In fact I addressed it quite
>>>> comprehensively. Your fuel flow meter is not up to the task of
>>>> measuring fuel flow with sufficient accuracy or repeatability
>>>> to demonstrate the so-fundamental-that-it-shouldn't-need-discussing,-
>>>> much-less-demonstrating principle of physics that's being discussed.
>>> So for all intents and purposes, the amount of additional fuel
>>> consumed when the headlights are turned on is immeasurable, so this
>>> "lights on = more fuel" business exists in theory only.
>> _Not_ immeasurable... just not measurable by a standard car
>> consumption gauge.
>> We have flow rate meters at work that are sensitive enough to measure
>> this effect.
> So does my car. It doesn't measure any change.
> '04 CBR1100XX
If your car flow rate meter was sensitive enough to measure this effect
then it would show the change (which exists) and since it doesn't show
any change it follows logically that the effect on you car consumption
is too small to be measured by your cars flow rate meter :)
From: G-S on 9 Feb 2007 02:32
Theo Bekkers wrote:
> jlittler(a)my-deja.com wrote:
>> (ceteris paribus),
> What kind of a bus is that?
>> (2) still not sure I'm explaining that particularly well
> Those of us that agreed with you understood it.
From: Andrew McKenna on 9 Feb 2007 03:28
<--- snipperage --->
> And your statement is indeed correct - there's a difference between
> the mechanical input and the mechanical load. Pure semantics of
> course. mechanical load (as torque) plus electrical load(as torque)
> equals mechanical input required(as torque). The mechanical load is a
> constant (ceteris paribus), the electrical load changes with, well,
> the electrical load <grin> (1). To be more accurate the torque/turning
> force that you have to provide to generate a current equal to the
> current being drawn is increased as the current required increases(2)
> (1) there obviously being more than one meaning of the word load in
> this context - one being current drawn, the other being turning force
> (2) still not sure I'm explaining that particularly well
I wasn't going to shove my oar in again but that's such a good
translation I can't resist it. Of course you have to spin the
electricity generating thing faster if you want more electricity,
nobody's arguing that you don't. What I was saying was that the
increased electrical load does not cause engine RPM to drop, because it
Simple test: drive a test vehicle (use Nev's) to a stadium with lights
and connect lights to a light circuit on the test vehicle (don't ask me
how, there seem to be a gadmillion electrical geniuses in here, you lot
figure it out). Step 2: turn on lights. If I'm wrong the test vehicle
will stall. If I'm right the lights won't come on but the test vehicle
will run normally.
From: Toosmoky on 9 Feb 2007 04:29
Andrew McKenna wrote:
> Simple test: drive a test vehicle (use Nev's) to a stadium with lights
> and connect lights to a light circuit on the test vehicle
No need. Our generators at work drop revs and sound as if they're under
load instantly when we turn on spotlights connected to them. There's no
doubt they'd be using more fuel.
Of course, whether that's a "waste" of petrol depends on your point of view.
I'm Toosmoky and that's my two bob's worth.
Work to ride, Ride to Work...