[GRRiders] Re: Lights being perpendicular

[Dan Barcellos]

I wish Eric hadn't used inflammatory rhetoric (i.e. BS).  Now we're going to
have to take it outside.

 

Eric, I commission you and a friend to make an experiment this evening.
Have a friend, with a walkie-talkie or cell phone; take your bike light
about a quarter of a mile down a straight street.  Make sure no car head
lights are shining in their direction, as bike tail light lenses are
designed to reflect auto headlights which would complicate the experiment.
Have the friend orient the light at different angles to your line of sight.
I guarantee the brightest and most visible orientation of the bike tail
light will be when the plane of its lense is perpendicular to your line of
sight.

 

As for your argument about the rolling terrain, I would suggest that the 90
degree vertical light will take best advantage of the broadening of the tail
light beam as the road ascends and descends to give the best possible
visibility rearward.

 

I'm sure Bill will use his best judgment on whether our tail lights are
close enough to 90 degrees to the street.  Our job is to do our best to make
it as close to 90 degrees as is practical.  I think Bill made it pretty
clear that disqualification looms if 90 degrees its not.

 

Dan

 

  _____  

From: goldrushriders-bounces at dbclist.org
[mailto:goldrushriders-bounces at dbclist.org] On Behalf Of ERIC THERESA
SIMMONS
Sent: Thursday, July 07, 2005 7:48 PM
To: goldrushriders at dbclist.org
Subject: [GRRiders] Re: Lights being perpendicular

 

    This perpedicularity of lights seems like just so much BS to me.

 

1. As an anesthesiologist at a trauma hospital every cyclist I have taken
care of who was hit riding at night had no head or tail lights, was wearing
dark clothing and had no reflective material. Randonneurs present the
antithesis of this model when riding at night.

 

2. The roads we ride are not flat. Therefore a cyclist with perpendicular
tail lights, beginning to ascend a hill will have lights pointed well below
the direct line of vision of a driver descending the hill just behind the
cyclist. There are almost limitless variations between the direct beam of
the tail light and the approaching observer. Regardless of the angle (within
reason) I have no trouble seeing cyclists ahead of me in the dark 1/2 to 1
mile ahead (depending on the terrain)  unless I am blinded by the headlights
of an on coming vehicle. 

 

3. Tail light lenses broadcast a wider beam of light than the headlights
that we use. The headlight beams are focused for the rider to see where
he/she is going and the taillights cast a broad beam for the rider to be
seen. Some thought was give to visibility by the engineers who designed the
taillights. Even at 145-160 degrees from the center of the beam most tail
lights are still very visible so, a few degrees off the perpendicular has
little or no effect on ones overall visibility, especially if one has two or
more tail lights.  

 

4. Bill, If you want to give a logical reason for having the lights
perpendicular it should be so that the brightest beam of the tail light is
not focused directly in the eyes of the cyclist behind you, just as the
blinking mode becomes distracting and irritating the bright center is
irritating and causes the night vision of the following cyclist to be
reduced.

 

I would especially like to here from our engineering trained randonneurs on
the subject as my diatribe is based on personal experience, observation and
a limited knowledge of physics.

 

Eric Simmons

 

 

----- Original Message ----- 

From: goldrushriders-request at dbclist.org 

To: goldrushriders at dbclist.org 

Sent: Thursday, July 07, 2005 1:00 PM

Subject: GoldRushRiders Digest, Vol 6, Issue 10

 

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