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On 3/18/2017 3:51 PM, Sir Ridesalot wrote:
On Saturday, March 18, 2017 at 3:12:02 PM UTC-4, Frank Krygowski wrote:
On 3/18/2017 2:29 PM, Jeff Liebermann wrote:
On Wed, 15 Mar 2017 14:08:44 -0400, Frank Krygowski
wrote:

Thing is, nobody's demonstrated any need for so much stationary "be
seen" light, beyond the usual "well, it _could_ happen" safety inflation
mentality.

True, but you're thinking like engineering, not marketing.

I do have too strong of a tendency to do that.

See http://dilbert.com/strip/2014-12-18

That has a place of honor on our refrigerator door.

--
- Frank Krygowski

Many many years ago I read an article and also books on bicycling that stated thatthe two most dangerous p;aces to ride a bicycle was #1 a parking lot and #2 an intersection.

That may be true. Parking lots are chaotic, but that has little to do
with standlights. Intersections are more dangerous than
non-intersection stretches of road, but the danger doesn't come from
being stationary. For legal cyclists, the sources of crashes are 1)
Right hooks 2) Left crosses, and 3) Pull-outs. In all those cases, the
cyclists are moving. Illegal cyclists can add other intersection
hazards, but again, those occur while the cyclist is moving.

You might try describing the specific traffic situation where a motorist
would be likely to hit a stationary cyclist because he has no headlight.

So, you guys are saying that having a bright standlight right where a lot of bicycling accidents happen (at an intersection) is a bad thing?

Nobody is saying it's a bad thing to have a standlight. However, I'm
saying it's not a critical thing. And it's certainly not true (as Joerg
implied) that there's a big risk in having a standlight that's dimmer
than a headlight, or one whose duration is only a couple minutes.

In Ohio, the law specifically states that dynamo lights that go out when
stationary are legal. I was not involved with getting that law passed,
but IIRC the Ohio Bicycle Federation was. They did so in part because
they judged there was no significant hazard.

I don't know about you but I like to know that a driver coming towards me at night whilst I'm stopped at an intersection can at least see my bicycle light.

Your personal preference is fine. But if the risk of crash due to lack
of standlight was really great, that source of crashes would have been
listed in the studies that examined car-bike crash sources. Those
studies have no such entries.

YMMV Why not paint your bike flat black and wear flat black clothing or camouflage clothing if being visible to other road users is of so little consequence even when you're stopped and they are moving?

sigh First, the color of a bike is completely negligible.

Second, I reject the idea that a cyclist is at fault if he chooses to
wear ordinary clothing, no matter its color.

IIRC, all but two U.S. states require no taillight, and allow mere rear
reflectors. I think if the resulting danger were great, there wouldn't
be 48 states disagreeing.

I do advocate taillights, but I think anything except the tiniest
coin-cell taillights are adequate. And back when I did night lighting
workshops with my bike club (where we observed lights on bikes to test
them) everyone else agreed.

And BTW, I think reflectors on pedals or cranks are extremely
conspicuous. I'd be more in favor of mandating them than mandating
taillights.

--
- Frank Krygowski

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On 3/18/2017 2:50 PM, Sir Ridesalot wrote:

snip

LOL, the world does not revolve around what YOU have noticed personally.

In the Odense study, cyclists with daytime bicycle lights had 32% fewer
accidents than the control group. The effect was particularly noticeable
during the summer season when the reduction is up to 40%. So it's when
the sun is brighter that there is even more of an advantage to DRLs.

You can see the same thing in your own town. It's especially noticeable
when cyclists are in a bicycle lane, closer to the curb than in a
traffic lane. They tend to blend in with the other stuff on the right
side of the road, such as parked cars.

BUNK!

LOL, that's a well-researched response.

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On 3/18/2017 5:35 PM, sms wrote:


In the Odense study, cyclists with daytime bicycle lights had 32% fewer
accidents than the control group. The effect was particularly noticeable
during the summer season when the reduction is up to 40%. So it's when
the sun is brighter that there is even more of an advantage to DRLs.

Let's talk about the origin and the details of that study.

First, it was initiated by Reelight, the company selling the lights. For
most scientifically competent people, that would at least indicate that
the details need critical examination.

Second, the group who got the lights was self-selected. Self-selection
is always regarded with high suspicion, because those choosing the
measure under study are almost guaranteed to be different than those who
do not make that choice.

In this case, the company offered free lights to those who would
participate. It's very likely that those choosing to get the lights
were the most fearful and careful cyclists - those who would have the
lowest crash rate in any case. IOW, the difference in crash rates
between self-selected and control groups would probably be as great if
the offer was for magic key fobs.

You can see the same thing in your own town. It's especially noticeable
when cyclists are in a bicycle lane, closer to the curb than in a
traffic lane. They tend to blend in with the other stuff on the right
side of the road, such as parked cars.

Don't ride in the gutter, Stephen.

--
- Frank Krygowski

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On 3/18/2017 3:54 PM, sms wrote:
On 3/18/2017 11:46 AM, Jeff Liebermann wrote:

snip

While the vests are unlikely to solve the problem, they do help and
are cheap enough.

Will they 100% solve the problem? Of course not. Will they help?
Definitely. We've had fatalities in Silicon Valley of pedestrians
walking at night on roads with drivers that have not been charged
because they legitimately claimed that they just did not see the
pedestrians.

There's this false narrative out there of "if there's not been a
double-blind study done, then we should ignore common sense, because no
one has conclusively proven XYZ."

There's also the false narrative saying if something may help to any
degree, it's foolish to not use it. However, the main proponent of that
"logic" still has not explained why he and his family don't use the
six-foot-tall bicycle flags of the 1970s.

https://americansafetyvest.com/wp-co...4/BikeFlag.jpg

There's no study that proves that making yourself more conspicuous at
night (or in the daytime for that matter) makes it less likely that
someone will inadvertently run you over, though in this case you might
want to accept the empirical evidence, extrapolate data from related
relevant studies, and use some common sense. Or not--if you have an
agenda that you're pushing.

In fact there has been at least one study on DRLs for bicycles,
https://www.bikelight.ca/pages/safety-first-study.

I've commented on that "study" in another post. It's right up there
with "Gleem toothpaste makes you 35% sexier."


If someone is expecting a graph of lumens or lux versus bicycle crashes,
then they will be waiting a long time.

The bottom line is what this article states: "You Have No Excuse Not to
Bike with a Light, Day or Night."
https://www.outsideonline.com/2064501/you-have-no-excuse-not-bike-light-day-or-night.

Take a look at the photo in that article. It appeared in an
advertisement in some bike magazines. What do you see? I saw a car and
a bike.

https://www.outsideonline.com/sites/...?itok=1zHaOkga

The photo was on the back cover of the magazine, lying face up for
several days before I even noticed what they were advertising. I
thought "Wait, what's this ad about?" Then I saw it was for the
taillight. Then I realized that the cyclist in the photo actually has a
taillight. Just as in real life, the cyclist - even in black clothing
against a dark background - is far more visible than the light.

I would advise him to get at least into the right tire track, though.
He's inviting close passes and adding to his risk of goat head or debris
punctures.


--
- Frank Krygowski

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On Sat, 18 Mar 2017 19:52:02 -0400, Frank Krygowski
wrote:
And BTW, I think reflectors on pedals or cranks are extremely
conspicuous. I'd be more in favor of mandating them than mandating
taillights.

Reflectors are already required in California:
http://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum= 21201

21201(d)

(1) A lamp emitting a white light that, while the bicycle is in
motion, illuminates the highway, sidewalk, or bikeway in front of the
bicyclist and is visible from a distance of 300 feet in front and from
the sides of the bicycle.

(2) A red reflector or a solid or flashing red light with a built-in
reflector on the rear that shall be visible from a distance of 500
feet to the rear when directly in front of lawful upper beams of
headlamps on a motor vehicle.

(3) A white or yellow reflector on each pedal, shoe, or ankle visible
from the front and rear of the bicycle from a distance of 200 feet.

(4) A white or yellow reflector on each side forward of the center of
the bicycle, and a white or red reflector on each side to the rear of
the center of the bicycle, except that bicycles that are equipped with
reflectorized tires on the front and the rear need not be equipped
with these side reflectors.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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On Sat, 18 Mar 2017 15:11:56 -0400, Frank Krygowski
wrote:

On 3/18/2017 2:29 PM, Jeff Liebermann wrote:
On Wed, 15 Mar 2017 14:08:44 -0400, Frank Krygowski
wrote:

Thing is, nobody's demonstrated any need for so much stationary "be
seen" light, beyond the usual "well, it _could_ happen" safety inflation
mentality.

True, but you're thinking like engineering, not marketing.

I do have too strong of a tendency to do that.
See http://dilbert.com/strip/2014-12-18
That has a place of honor on our refrigerator door.

I can see that this discussion is going to be all uphill. I'll be
merciful and uncharacteristically brief.

I worked for a company run by engineers that dug a hole for itself and
then jump in by doing very little market research and ignoring their
own marketing people. Designing a working product is only part of the
puzzle. Packaging, merchandising, and selling it in a manner that
customers will want to buy it is far more difficult because it's NOT
an exact science like engineering. This is one reason that engineers
fail to appreciate marketeers. It works the other way, where
engineers are pathological incapable of letting go of their design and
will continue to "improve" the design long after the customer has left
and gone elsewhere.

Incidentally, having one foot in each swamp, I had the dubious honor
of being called a traitor by both sides. I really didn't appreciate
the problem until that happened. Also, I tend to identify with
Dilbert's PHB (pointy hair boss), partly because I've lost enough hair
to look like him, but also because I can see myself in similar
situations. Being in the middle between engineering, marketing,
sales, and production is not my idea of fun job. I did it for a while
running my father's company and hated it.


Drivel:
https://trackmaven.com/blog/national-days-calendar/
Hmmm... Today (Mar 18) is "National Supreme Sacrifice Day".
I wonder if they mean human sacrifice?



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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On 3/18/2017 10:23 PM, Jeff Liebermann wrote:
On Sat, 18 Mar 2017 19:52:02 -0400, Frank Krygowski
wrote:
And BTW, I think reflectors on pedals or cranks are extremely
conspicuous. I'd be more in favor of mandating them than mandating
taillights.

Reflectors are already required in California:
http://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum= 21201

21201(d)

(1) A lamp emitting a white light that, while the bicycle is in
motion, illuminates the highway, sidewalk, or bikeway in front of the
bicyclist and is visible from a distance of 300 feet in front and from
the sides of the bicycle.

(2) A red reflector or a solid or flashing red light with a built-in
reflector on the rear that shall be visible from a distance of 500
feet to the rear when directly in front of lawful upper beams of
headlamps on a motor vehicle.

(3) A white or yellow reflector on each pedal, shoe, or ankle visible
from the front and rear of the bicycle from a distance of 200 feet.

(4) A white or yellow reflector on each side forward of the center of
the bicycle, and a white or red reflector on each side to the rear of
the center of the bicycle, except that bicycles that are equipped with
reflectorized tires on the front and the rear need not be equipped
with these side reflectors.

I think most states are similar. But note the phrase "while the bicycle
is in motion."


--
- Frank Krygowski

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On Sunday, March 19, 2017 at 12:34:21 AM UTC-4, Frank Krygowski wrote:
On 3/18/2017 10:23 PM, Jeff Liebermann wrote:
On Sat, 18 Mar 2017 19:52:02 -0400, Frank Krygowski
wrote:
And BTW, I think reflectors on pedals or cranks are extremely
conspicuous. I'd be more in favor of mandating them than mandating
taillights.

Reflectors are already required in California:
http://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum= 21201

21201(d)

(1) A lamp emitting a white light that, while the bicycle is in
motion, illuminates the highway, sidewalk, or bikeway in front of the
bicyclist and is visible from a distance of 300 feet in front and from
the sides of the bicycle.

(2) A red reflector or a solid or flashing red light with a built-in
reflector on the rear that shall be visible from a distance of 500
feet to the rear when directly in front of lawful upper beams of
headlamps on a motor vehicle.

(3) A white or yellow reflector on each pedal, shoe, or ankle visible
from the front and rear of the bicycle from a distance of 200 feet.

(4) A white or yellow reflector on each side forward of the center of
the bicycle, and a white or red reflector on each side to the rear of
the center of the bicycle, except that bicycles that are equipped with
reflectorized tires on the front and the rear need not be equipped
with these side reflectors.

I think most states are similar. But note the phrase "while the bicycle
is in motion."


--
- Frank Krygowski

I don't know about you people butt... When I'm stopped at an intersection at night I like to have a light shining forward as well as a rear red light so that vehicles approaching me and turning can see there is something in front of them. Ditto for when just staarting from a stop and not yet up to soeed. that seems to be a time when there are a lot of cars that will turn infront of a bicyclist because the driver didn't see the bicyclist. A bicyclist can also be hidden from an approaching and or approaching and turning driver, by the headlights of a car or truck behind the bicyclist. You guys can go ahead and play Russian Roulette with cars at intersections at night because you have no working light giving forthlight from your bicycle there. I'll keep my light ON at those intersections so that other road users can see a bicycle is there.

Cheers

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On Sunday, March 19, 2017 at 2:06:24 AM UTC-7, Sir Ridesalot wrote:

I don't know about you people butt... When I'm stopped at an intersection at night I like to have a light shining forward as well as a rear red light so that vehicles approaching me and turning can see there is something in front of them. Ditto for when just staarting from a stop and not yet up to soeed. that seems to be a time when there are a lot of cars that will turn infront of a bicyclist because the driver didn't see the bicyclist. A bicyclist can also be hidden from an approaching and or approaching and turning driver, by the headlights of a car or truck behind the bicyclist. You guys can go ahead and play Russian Roulette with cars at intersections at night because you have no working light giving forthlight from your bicycle there. I'll keep my light ON at those intersections so that other road users can see a bicycle is there.

Cheers

Yes, that's extremely important.

One intersection I go through several times a week https://goo.gl/maps/uUrDJjyYMeM2 has most of the opposing traffic turning left. Without a good light, invariably they will turn directly in front of a bicycle going straight across, but if the cyclist has a light they will invariably yield the right of way.

The cross street is six lanes, plus two left turn lanes, plus two bicycle lanes, plus a median. So a poor light is unlikely to get the vehicles' on the other side's attention. It's especially necessary to have a good light if you plan your approach as the light is turning green so you don't have to stop pr slow down.

Those that rail against proper bicycle lighting have the mindset that it's not necessary because the cyclists can instead take evasive action, and constantly be yielding to vehicles that can't see them even when the cyclist has the right-of-way.

If we are going to advocate for "transportational cycling" then we should be exerting our rights to the road, but if vehicles aren't aware of our presence that's hard to do, and it's getting harder with so much distracted driving.

I'm glad that the Odense study proved the value of daytime flashing lights. It's a good step forward in convincing those that oppose cyclists making themselves visible that in fact conspicuousness is a good idea. Of course those that oppose conspicuousness will try to find ways to attack the study, just as they try to attack helmet studies.

Too bad the bank isn't open today. I have a stack of checks from the manufacturers of good bicycle lights that I have to deposit.

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On 3/18/2017 2:51 PM, Sir Ridesalot wrote:
On Saturday, March 18, 2017 at 3:12:02 PM UTC-4, Frank Krygowski wrote:
On 3/18/2017 2:29 PM, Jeff Liebermann wrote:
On Wed, 15 Mar 2017 14:08:44 -0400, Frank Krygowski
wrote:

Thing is, nobody's demonstrated any need for so much stationary "be
seen" light, beyond the usual "well, it _could_ happen" safety inflation
mentality.

True, but you're thinking like engineering, not marketing.

I do have too strong of a tendency to do that.

See http://dilbert.com/strip/2014-12-18

That has a place of honor on our refrigerator door.

--
- Frank Krygowski

Many many years ago I read an article and also books on bicycling that stated thatthe two most dangerous p;aces to ride a bicycle was #1 a parking lot and #2 an intersection. So, you guys are saying that having a bright standlight right where a lot of bicycling accidents happen (at an intersection) is a bad thing? I don't know about you but I like to know that a driver coming towards me at night whilst I'm stopped at an intersection can at least see my bicycle light.
YMMV Why not paint your bike flat black and wear flat black clothing or camouflage clothing if being visible to other road users is of so little consequence even when you're stopped and they are moving?

Cheers


*ahem* I wear mostly black on both of my black bicycles. So
far so good...

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

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On 3/18/2017 9:47 PM, Jeff Liebermann wrote:
On Sat, 18 Mar 2017 15:11:56 -0400, Frank Krygowski
wrote:

On 3/18/2017 2:29 PM, Jeff Liebermann wrote:
On Wed, 15 Mar 2017 14:08:44 -0400, Frank Krygowski
wrote:

Thing is, nobody's demonstrated any need for so much stationary "be
seen" light, beyond the usual "well, it _could_ happen" safety inflation
mentality.

True, but you're thinking like engineering, not marketing.

I do have too strong of a tendency to do that.
See http://dilbert.com/strip/2014-12-18
That has a place of honor on our refrigerator door.

I can see that this discussion is going to be all uphill. I'll be
merciful and uncharacteristically brief.

I worked for a company run by engineers that dug a hole for itself and
then jump in by doing very little market research and ignoring their
own marketing people. Designing a working product is only part of the
puzzle. Packaging, merchandising, and selling it in a manner that
customers will want to buy it is far more difficult because it's NOT
an exact science like engineering. This is one reason that engineers
fail to appreciate marketeers. It works the other way, where
engineers are pathological incapable of letting go of their design and
will continue to "improve" the design long after the customer has left
and gone elsewhere.

Incidentally, having one foot in each swamp, I had the dubious honor
of being called a traitor by both sides. I really didn't appreciate
the problem until that happened. Also, I tend to identify with
Dilbert's PHB (pointy hair boss), partly because I've lost enough hair
to look like him, but also because I can see myself in similar
situations. Being in the middle between engineering, marketing,
sales, and production is not my idea of fun job. I did it for a while
running my father's company and hated it.


Drivel:
https://trackmaven.com/blog/national-days-calendar/
Hmmm... Today (Mar 18) is "National Supreme Sacrifice Day".
I wonder if they mean human sacrifice?




Quoting the great Peter Drucker, "Nothing gets done until
somebody sells something." All the excellence of your
design is for nothing unless you can pay the bills and earn
a profit.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

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On 2017-03-18 11:00, Jeff Liebermann wrote:
On Fri, 17 Mar 2017 17:03:19 -0700, Joerg
wrote:

However, every time I asked dirt
bikers who venture out into the sticks in Nevada they said that they
tried their smart phones but that it really doesn't work well without a
Garmin or other native GPS device.

I've had the same experience when I try to run the GPS in "airplane
mode". The GPS uses location data from the cell sites (AGPS) to
improve its E911 accuracy and shorten acquisition time. Turn off the
cellular part of the phone, or try to use GPS in an area where there
are no cell sites is a problem.

"Using an Android GPS in Airplane Mode"
http://backcountrynavigator.com/using-android-gps-airplane-mode/

There are also issues with the antenna. Size matters and the bigger
patch antennas used in handheld GPS receivers offers much better
sensitivity and view of the sky.

I have a collection of about 10 assorted GPS receivers. Occasionally,
I do a comparison of performance in challenging areas (hills,
mountains, trees, indoors, underground garages, highly reflective
environments, RF polluted environments, etc). If I have a nearby cell
site to use as a starting or reference point, my Moto G smartphone
does quite well. My Samsung S6, not so well but good enough. However,
if I go into "airplane mode" to save battery power, performance sucks.
The main problem is that without the position sanity check provided by
AGPS, the smartphone GPS will produce wildly erratic positions caused
by reflections, often miles away from my actual location. Some of the
handheld mapping GPS receivers do the same thing, but not as badly.


Miles is bad. That means a position indication is useless for any
serious trail riding. Are at least the maps and the satellite view as
good as on a PC? As long as it buffers enough before going off-grid that
would help because I can fix my position pretty well via the use of
landmarks. Good old triangulation.


There is also some mapping trickery involved when using maps and AGPS.
In order to improve (or fake) accuracy for E911, mapping smartphone
apps like to round off positions to coincide with a roadway. It's a
fair assumption that someone using a GPS map program would be on some
kind of road. That's great, until you ride off the road and your GPS
tracker thinks you're still on the roadway. So far, it hasn't been a
problem.


With me that's a problem because my favorite routes are off-road. I try
to avoid raods whenever possible for many reasons. Like the one
yesterday where a driver came very close and leaned on the horn in an
attempt to push me from the lane to the side. No danger because he had
slowed down to my pace but such low-lifes with a drivers license are
annoying. And dangerous, especially when they are soused or nowadays
high on whatever.


You really need to get with the program and buy yourself an iPhone 7+,

Only over my dead body :-)

I'll resist the temptation to say something clever about your
destructive testing methods.


I wore out the BB on my road bike. Again :-(

But it was 40 miles of fun (except for the road part)

--
Regards, Joerg

http://www.analogconsultants.com/

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On 3/19/2017 8:33 AM, AMuzi wrote:

snip

Quoting the great Peter Drucker, "Nothing gets done until somebody sells
something." All the excellence of your design is for nothing unless you
can pay the bills and earn a profit.

Yet there are some that design stuff and give away the designs out of
the goodness of their hearts. Look at all the open-source software. Look
at all the people that design stuff because they like to do it, not as
part of their regular jobs.

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On 3/19/2017 5:06 AM, Sir Ridesalot wrote:
On Sunday, March 19, 2017 at 12:34:21 AM UTC-4, Frank Krygowski wrote:
On 3/18/2017 10:23 PM, Jeff Liebermann wrote:
On Sat, 18 Mar 2017 19:52:02 -0400, Frank Krygowski
wrote:
And BTW, I think reflectors on pedals or cranks are extremely
conspicuous. I'd be more in favor of mandating them than mandating
taillights.

Reflectors are already required in California:
http://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum= 21201

21201(d)

(1) A lamp emitting a white light that, while the bicycle is in
motion, illuminates the highway, sidewalk, or bikeway in front of the
bicyclist and is visible from a distance of 300 feet in front and from
the sides of the bicycle.

(2) A red reflector or a solid or flashing red light with a built-in
reflector on the rear that shall be visible from a distance of 500
feet to the rear when directly in front of lawful upper beams of
headlamps on a motor vehicle.

(3) A white or yellow reflector on each pedal, shoe, or ankle visible
from the front and rear of the bicycle from a distance of 200 feet.

(4) A white or yellow reflector on each side forward of the center of
the bicycle, and a white or red reflector on each side to the rear of
the center of the bicycle, except that bicycles that are equipped with
reflectorized tires on the front and the rear need not be equipped
with these side reflectors.

I think most states are similar. But note the phrase "while the bicycle
is in motion."


--
- Frank Krygowski

I don't know about you people butt... When I'm stopped at an intersection at night I like to have a light shining forward as well as a rear red light so that vehicles approaching me and turning can see there is something in front of them. Ditto for when just staarting from a stop and not yet up to soeed. that seems to be a time when there are a lot of cars that will turn infront of a bicyclist because the driver didn't see the bicyclist. A bicyclist can also be hidden from an approaching and or approaching and turning driver, by the headlights of a car or truck behind the bicyclist. You guys can go ahead and play Russian Roulette with cars at intersections at night because you have no working light giving forthlight from your bicycle there. I'll keep my light ON at those intersections so that other road users can see a bicycle is there.

I like to have some reflectors on my bike. I also like to have a
handlebar bag, a full-sized frame pump, fenders and other items.

But I won't claim you're playing "Russian Roulette" if you make
different choices - especially if I lack decent data.

--
- Frank Krygowski

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On Sun, 19 Mar 2017 08:34:51 -0700, Joerg
wrote:
Miles is bad. That means a position indication is useless for any
serious trail riding.

Not exactly. It depends on what you're doing. If you try to plot
your ride, you might get some screwed up data points mixed in with the
data. For example, my last hike into the bottom of a local canyon
yielded a maximum altitude of 3,000 feet higher than the ground. There
was only one or two bad data points, but it was enough to screw up all
the statistics. Same with maximum speeds traveled, where the distance
covered between a real position indication and a bogus point or two is
high enough for me to claim breaking the sound barrier.

Mapping software authors know about all this and do their best to
compensate. The most common and best method is to do a sanity check
on all positions. If the GPS suddenly claims you've instantly moved
many miles, that point gets dropped. You probably won't see garbage
data on your smartphone or mapping GPS because of this feature. You
will see garbage if you use raw NMEA-183 data in some application. If
you want to see if you have a potential problem, just connect a data
logger to the GPS and collect some $GPGLL sentences. Write a program
that looks for large changes in adjacent sentences. The glitches, if
present, should be drastic and obvious.

Somewhere in my mess is a Windoze program that takes this data and
provide both graphical and tabular accuracy statistics. I used to use
it when we had to deal with selective availability. It's kinda neat.
You park yourself in a highly reflective location (bottom of a rock
canyon) and record about 30 mins of position data. Position
excursions on the display are obvious. I use it for averaging
readings over a long period in order to obtain better accuracy.

Are at least the maps and the satellite view as
good as on a PC? As long as it buffers enough before going off-grid that
would help because I can fix my position pretty well via the use of
landmarks. Good old triangulation.

I'm not sure. Everything depends on the antenna sensitivity and
bandwidth. There's a huge difference in performance between an
antenna that uses a choke ring to reduce ground reflections as on
survey receivers:
https://en.wikipedia.org/wiki/Choke_ring_antenna
and a smartphone that uses a tiny ceramic patch antenna. These
articles cover the problem quite nicely:
https://www.u-blox.com/sites/default/files/products/documents/GPS-Antenna_AppNote_%28GPS-X-08014%29.pdf?utm_source=en%2Fimages%2Fdownloads%2F Product_Docs%2FGPS_Antennas_ApplicationNote%28GPS-X-08014%29.pdf
http://www.taoglas.com/wp-content/uploads/2015/07/Internal-GPS-Active-Patch-AntennaAPN-13-8-002.B.pdf
Hmmm... probably more than you want to know. Suffice to say that the
smaller the antenna, the narrower the usable bandwidth. This is
important because small antennas work very badly with WAAS and barely
can handle the L1/L2 bands. Gain also suffers. From the Taoglas
article:
Typical peak gain for GPS patch antennas on standardized
ground planes are as follows:
25mm Patch 5 dBi
18mm Patch 2 dBi
15mm Patch 1 dBi
12mm Patch 0.5 dBi
10mm Patch -2 dBi
By comparison to what's found in a smartphone, these patch antennas
are HUGE. I can't seem to find the smartphone GPS antenna vendor, but
as I vaguely recall, the typical gain was about -8dBi with a rather
narrow view of the sky.

Anyway, back to your question... If you look at the antenna, and
assume that the receivers are all rather similar, your performance
will be almost totally dependent on the GPS antenna.

With me that's a problem because my favorite routes are off-road. I try
to avoid raods whenever possible for many reasons. Like the one
yesterday where a driver came very close and leaned on the horn in an
attempt to push me from the lane to the side. No danger because he had
slowed down to my pace but such low-lifes with a drivers license are
annoying. And dangerous, especially when they are soused or nowadays
high on whatever.

Well, you could weaponize your bicycle to act as a deterrent.
https://www.google.com/search?q=bicycle+gun&tbm=isch

I wore out the BB on my road bike. Again :-(
But it was 40 miles of fun (except for the road part)

Sigh. At least you wore it out and didn't break it. Out of
curiosity, what wore out? Bearings? Raceway? Seals? Mechanical
doping motor?


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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On Sun, 19 Mar 2017 10:29:45 -0700, Jeff Liebermann
wrote:

Somewhere in my mess is a Windoze program that takes this data and
provide both graphical and tabular accuracy statistics. I used to use
it when we had to deal with selective availability. It's kinda neat.
You park yourself in a highly reflective location (bottom of a rock
canyon) and record about 30 mins of position data. Position
excursions on the display are obvious. I use it for averaging
readings over a long period in order to obtain better accuracy.

Foundit.

Visual GPS:
http://www.visualgps.net/#visualgps-content
It's free and old but works nicely.

Visual GPS XP works somewhat better, but costs $10:
http://www.visualgps.net/#visualgpsxp-content

New, improved, and free is Visual GPS View:
http://www.visualgps.net/#visualgpsview-content

All these will graphically show any radical excursions in position.

I have several battery powered, BlueGoof GPS receivers. They're quite
convenient for testing with VisualGPS. However, I prefer to use an
RS232 data logger, which works on any GPS. After collecting data for
maybe 30 minutes, I dump the output into the Visual GPS program and
inspect the resulting mess.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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On Sun, 19 Mar 2017 10:29:45 -0700, Jeff Liebermann
wrote:

On Sun, 19 Mar 2017 08:34:51 -0700, Joerg
wrote:
Miles is bad. That means a position indication is useless for any
serious trail riding.

Not exactly. It depends on what you're doing. If you try to plot
your ride, you might get some screwed up data points mixed in with the
data. For example, my last hike into the bottom of a local canyon
yielded a maximum altitude of 3,000 feet higher than the ground. There
was only one or two bad data points, but it was enough to screw up all
the statistics. Same with maximum speeds traveled, where the distance
covered between a real position indication and a bogus point or two is
high enough for me to claim breaking the sound barrier.

Mapping software authors know about all this and do their best to
compensate. The most common and best method is to do a sanity check
on all positions. If the GPS suddenly claims you've instantly moved
many miles, that point gets dropped. You probably won't see garbage
data on your smartphone or mapping GPS because of this feature. You
will see garbage if you use raw NMEA-183 data in some application. If
you want to see if you have a potential problem, just connect a data
logger to the GPS and collect some $GPGLL sentences. Write a program
that looks for large changes in adjacent sentences. The glitches, if
present, should be drastic and obvious.

I know nothing of U.S. mapping but I can assure you that using marine
charts there is a definite problem, in some cases, in comparing GPS
positions with existing charts. One of my friends favorite anchorages,
in the S. Philippines, is on dry land according to the current marine
chart of the area :-)

To the extent that some, perhaps many, charts include offset
information for use with GPS.
--
Cheers,

John B.

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On Mon, 20 Mar 2017 07:48:44 +0700, John B.
wrote:

I know nothing of U.S. mapping but I can assure you that using marine
charts there is a definite problem, in some cases, in comparing GPS
positions with existing charts. One of my friends favorite anchorages,
in the S. Philippines, is on dry land according to the current marine
chart of the area :-)

To the extent that some, perhaps many, charts include offset
information for use with GPS.

There are plenty of ways to screw up a map. The most common is to use
the wrong datum. WGS84 is the most common for GPS. However many
countries have their own. For example, the USGS maps are still NAD27
and are sloooooowly converting over to NAD83. At one time Google Maps
and Google Earth used the wrong datum for Santa Cruz CA and managed to
shift the entire city to the east by 200 ft. That wasn't fatal for
land navigation, but allegedly caused a problem when some fisherman
tried to navigate his way into Santa Cruz yacht harbor in the fog and
missed by 200ft.

Looks like the Philippines uses PRS92 datum.
http://georepository.com/datum_6683/Philippine-Reference-System-1992.html
There is also the Luzon Datum of 1911:
https://en.wikipedia.org/wiki/Luzon_Datum_of_1911
There are also various zones in the Philippines to be considered:
http://tool-online.com/index/systemes-coordonnees/philippines.html

My guess(tm) is that you'll find that the GPS is set for one datum
(probably WGS84), while the printed map is based on PRS92 or earlier.
The document mentioned in the above Wikipedia page footnotes, "Status
of the geodetic infrastructure of the Philippines" looks interesting
and will probably have come clues on conversions and errors. However,
the link doesn't work.

Looks like some tools are available:
https://www.google.com/search?q=convert+prs92+to+wgs84

Looks like the difference is -128 meters E-W and -67 meters NS.
http://georepository.com/transformation_15708/PRS92-to-WGS-84-1.html
That's plenty of room to put your friends anchorage on dry land.

There are other sources of error, but this is the most likely.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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On Sun, 19 Mar 2017 19:59:50 -0700, Jeff Liebermann
wrote:

On Mon, 20 Mar 2017 07:48:44 +0700, John B.
wrote:

I know nothing of U.S. mapping but I can assure you that using marine
charts there is a definite problem, in some cases, in comparing GPS
positions with existing charts. One of my friends favorite anchorages,
in the S. Philippines, is on dry land according to the current marine
chart of the area :-)

To the extent that some, perhaps many, charts include offset
information for use with GPS.

There are plenty of ways to screw up a map. The most common is to use
the wrong datum. WGS84 is the most common for GPS. However many
countries have their own. For example, the USGS maps are still NAD27
and are sloooooowly converting over to NAD83. At one time Google Maps
and Google Earth used the wrong datum for Santa Cruz CA and managed to
shift the entire city to the east by 200 ft. That wasn't fatal for
land navigation, but allegedly caused a problem when some fisherman
tried to navigate his way into Santa Cruz yacht harbor in the fog and
missed by 200ft.

Looks like the Philippines uses PRS92 datum.
http://georepository.com/datum_6683/Philippine-Reference-System-1992.html
There is also the Luzon Datum of 1911:
https://en.wikipedia.org/wiki/Luzon_Datum_of_1911
There are also various zones in the Philippines to be considered:
http://tool-online.com/index/systemes-coordonnees/philippines.html

My guess(tm) is that you'll find that the GPS is set for one datum
(probably WGS84), while the printed map is based on PRS92 or earlier.
The document mentioned in the above Wikipedia page footnotes, "Status
of the geodetic infrastructure of the Philippines" looks interesting
and will probably have come clues on conversions and errors. However,
the link doesn't work.

Looks like some tools are available:
https://www.google.com/search?q=convert+prs92+to+wgs84

Looks like the difference is -128 meters E-W and -67 meters NS.
http://georepository.com/transformation_15708/PRS92-to-WGS-84-1.html
That's plenty of room to put your friends anchorage on dry land.

There are other sources of error, but this is the most likely.


The marine GPS' that I've used were all WGS84.

Generally speaking those who sail outside the U.S., are using British
Admiralty charts, or copies there of. I used to buy Thai charts from
the Thai Navy and they were based on Admiralty charts. I don't
remember but I think that they were not WGS84.

But datum aside, I had a copy of a chart of an island in the S.
Pacific and the notes stated, it was based on surveys made by the HMS
something or another, in 1790-something. I always thought that if I
ever got onto the S. Pacific that I would approach those islands in
the daylight with great care :-)

--
Cheers,

John B.

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On Mon, 20 Mar 2017 12:25:07 +0700, John B.
wrote:

The marine GPS' that I've used were all WGS84.

Yep. That's the usual default setting.

Generally speaking those who sail outside the U.S., are using British
Admiralty charts, or copies there of. I used to buy Thai charts from
the Thai Navy and they were based on Admiralty charts. I don't
remember but I think that they were not WGS84.

NOAA nautical maps use NAD83 (which is very close to WGS84).
USGS uses NAD27 but is slowly moving to NAD83.
Google Earth uses WGS84.
Geocaching uses WGS84.

Here's what the military thinks of "civilian" charts:
http://msi.nga.mil/MSISiteContent/StaticFiles/Files/NautChrts_GPS_index.htm
"Isolated datums, such as those used to position many islands
in the Pacific Ocean, can be in error by a half mile or more
(see figure). The datum shift to WGS 84 can be quite large,
depending on the area of the world and the local datum in use."

See the chart of Farallon De Pajaros Island, which requires a 1/2
nautical mile shift for the map to agree with GPS.
http://msi.nga.mil/MSISiteContent/StaticFiles/Files/island.jpg

But datum aside, I had a copy of a chart of an island in the S.
Pacific and the notes stated, it was based on surveys made by the HMS
something or another, in 1790-something. I always thought that if I
ever got onto the S. Pacific that I would approach those islands in
the daylight with great care :-)

Possibly Captain James Cook, who went through the south pacific
between 1768 to 1771.
https://en.wikipedia.org/wiki/European_and_American_voyages_of_scientific_explor ation

I have a nice Tamaya sextant, out of date HO 229/249 tables, and some
charts. It's not very practical these days, but it does help one
understand how such things work.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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On Sun, 19 Mar 2017 23:59:36 -0700, Jeff Liebermann
wrote:

On Mon, 20 Mar 2017 12:25:07 +0700, John B.
wrote:

The marine GPS' that I've used were all WGS84.

Yep. That's the usual default setting.

Generally speaking those who sail outside the U.S., are using British
Admiralty charts, or copies there of. I used to buy Thai charts from
the Thai Navy and they were based on Admiralty charts. I don't
remember but I think that they were not WGS84.

NOAA nautical maps use NAD83 (which is very close to WGS84).
USGS uses NAD27 but is slowly moving to NAD83.
Google Earth uses WGS84.
Geocaching uses WGS84.

Here's what the military thinks of "civilian" charts:
http://msi.nga.mil/MSISiteContent/StaticFiles/Files/NautChrts_GPS_index.htm
"Isolated datums, such as those used to position many islands
in the Pacific Ocean, can be in error by a half mile or more
(see figure). The datum shift to WGS 84 can be quite large,
depending on the area of the world and the local datum in use."

See the chart of Farallon De Pajaros Island, which requires a 1/2
nautical mile shift for the map to agree with GPS.
http://msi.nga.mil/MSISiteContent/StaticFiles/Files/island.jpg

But datum aside, I had a copy of a chart of an island in the S.
Pacific and the notes stated, it was based on surveys made by the HMS
something or another, in 1790-something. I always thought that if I
ever got onto the S. Pacific that I would approach those islands in
the daylight with great care :-)

Possibly Captain James Cook, who went through the south pacific
between 1768 to 1771.
https://en.wikipedia.org/wiki/European_and_American_voyages_of_scientific_explor ation

:-) No, it was later than that :-)

I have a nice Tamaya sextant, out of date HO 229/249 tables, and some
charts. It's not very practical these days, but it does help one
understand how such things work.

Way back when, I went to considerable effort to learn proper
navigation. Sextant, HO tables and lessons from the lead navigator in
a B-52 squadron. What sort of took the shine off the effort was when I
did the usual three shot position and got a "cocked hat"that was about
a mile and a half on each side. When I told the Major about it he
commented that I was doing real good. I replied that I didn't think
that a triangle that was a mile and a half on each side wasn't very
accurate he assured me that it was "pretty good for celestial
navigation.... which is why we don't use that for the B-52's" :-)
--
Cheers,

John B.

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On Mon, 20 Mar 2017 18:33:51 +0700, John B.
wrote:
Way back when, I went to considerable effort to learn proper
navigation. Sextant, HO tables and lessons from the lead navigator in
a B-52 squadron. What sort of took the shine off the effort was when I
did the usual three shot position and got a "cocked hat"that was about
a mile and a half on each side. When I told the Major about it he
commented that I was doing real good. I replied that I didn't think
that a triangle that was a mile and a half on each side wasn't very
accurate he assured me that it was "pretty good for celestial
navigation.... which is why we don't use that for the B-52's" :-)

Accurate navigation with an aviation sextant is far more difficult
than marine navigation. If you were doing celestial or lunar
navigation on the ground, using an averaging bubble sextant artificial
horizon, I would say 1.5 miles was doing very good. If you were doing
it while flying, amazingly good.

I'm told that marine navigation is easier. Many years ago, I dragged
a gaggle of middle skool slackers to the end of the local breakwater,
which features a miniature lighthouse that's almost exactly at -122.0
deg longitude.
http://www.lighthousefriends.com/light.asp?ID=836
It was a clear day and the horizon was clearly defined. It was almost
noon, so I started by showing them how to take a noon sight. I was a
bit more than a nautical mile off. Oops. I brought along a WWV
receiver for doing latitude, but the signal was too weak to be usable.
Using someone's inaccurate wrist watch, I located our position about 5
nautical miles away. Lunch and a side trip to the local amusement
park was sufficient to salvage my reputation.

Some additional navigation horror stories using Omega, Loran (lane
skipping), Navsat, inertial navigation, and direction finding using
radio towers, but this is getting too far of topic (whatever that
might be). The tower story is interesting. The FCC database records
the "location" of each radio station licensee. One might assume that
this means the location of the transmitting tower. Instead, it's
usually the location of the studios or offices. Someone published a
navigation map using the FCC locations instead of the tower locations
resulting in RDF (radio direction finding) receiving a bad reputation
for poor accuracy when used for navigation.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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On 2017-03-19 15:01, Jeff Liebermann wrote:
On Sun, 19 Mar 2017 10:29:45 -0700, Jeff Liebermann
wrote:

Somewhere in my mess is a Windoze program that takes this data and
provide both graphical and tabular accuracy statistics. I used to use
it when we had to deal with selective availability. It's kinda neat.
You park yourself in a highly reflective location (bottom of a rock
canyon) and record about 30 mins of position data. Position
excursions on the display are obvious. I use it for averaging
readings over a long period in order to obtain better accuracy.

Foundit.

Visual GPS:
http://www.visualgps.net/#visualgps-content
It's free and old but works nicely.

Visual GPS XP works somewhat better, but costs $10:
http://www.visualgps.net/#visualgpsxp-content

New, improved, and free is Visual GPS View:
http://www.visualgps.net/#visualgpsview-content

All these will graphically show any radical excursions in position.

I have several battery powered, BlueGoof GPS receivers. They're quite
convenient for testing with VisualGPS. However, I prefer to use an
RS232 data logger, which works on any GPS. After collecting data for
maybe 30 minutes, I dump the output into the Visual GPS program and
inspect the resulting mess.


Nice, but its kind of tough to schlepp all this along on an MTB through
dirt and stuff.

--
Regards, Joerg

http://www.analogconsultants.com/

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On Monday, March 20, 2017 at 8:48:05 AM UTC-7, Jeff Liebermann wrote:
On Mon, 20 Mar 2017 18:33:51 +0700, John B.
wrote:
Way back when, I went to considerable effort to learn proper
navigation. Sextant, HO tables and lessons from the lead navigator in
a B-52 squadron. What sort of took the shine off the effort was when I
did the usual three shot position and got a "cocked hat"that was about
a mile and a half on each side. When I told the Major about it he
commented that I was doing real good. I replied that I didn't think
that a triangle that was a mile and a half on each side wasn't very
accurate he assured me that it was "pretty good for celestial
navigation.... which is why we don't use that for the B-52's" :-)

Accurate navigation with an aviation sextant is far more difficult
than marine navigation. If you were doing celestial or lunar
navigation on the ground, using an averaging bubble sextant artificial
horizon, I would say 1.5 miles was doing very good. If you were doing
it while flying, amazingly good.

snip

Lookit that, 50 years later, you're finally exonerated.

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On 2017-03-19 10:29, Jeff Liebermann wrote:
On Sun, 19 Mar 2017 08:34:51 -0700, Joerg
wrote:
Miles is bad. That means a position indication is useless for any
serious trail riding.

Not exactly. It depends on what you're doing. If you try to plot
your ride, you might get some screwed up data points mixed in with the
data. For example, my last hike into the bottom of a local canyon
yielded a maximum altitude of 3,000 feet higher than the ground.


That's a problem. One of the challenges with MTB riding is that a
satellite map might show a trail but then two things can happen:

After many, many miles you arrive at a fence with a sign stating in no
uncertain terms that this is not to be crossed.

Or, after a few miles you find that the trail leads over the steepest
hill this side of the Klondike and you are almost out of time as it is.

Regarding altitude at my current position I can take along my
parachuting altimeter. It is very rugged and accurate.

... There
was only one or two bad data points, but it was enough to screw up all
the statistics. Same with maximum speeds traveled, where the distance
covered between a real position indication and a bogus point or two is
high enough for me to claim breaking the sound barrier.

Mapping software authors know about all this and do their best to
compensate. The most common and best method is to do a sanity check
on all positions. If the GPS suddenly claims you've instantly moved
many miles, that point gets dropped. You probably won't see garbage
data on your smartphone or mapping GPS because of this feature. You
will see garbage if you use raw NMEA-183 data in some application. If
you want to see if you have a potential problem, just connect a data
logger to the GPS and collect some $GPGLL sentences. Write a program
that looks for large changes in adjacent sentences. The glitches, if
present, should be drastic and obvious.

Somewhere in my mess is a Windoze program that takes this data and
provide both graphical and tabular accuracy statistics. I used to use
it when we had to deal with selective availability. It's kinda neat.
You park yourself in a highly reflective location (bottom of a rock
canyon) and record about 30 mins of position data. Position
excursions on the display are obvious. I use it for averaging
readings over a long period in order to obtain better accuracy.

Are at least the maps and the satellite view as
good as on a PC? As long as it buffers enough before going off-grid that
would help because I can fix my position pretty well via the use of
landmarks. Good old triangulation.

I'm not sure. Everything depends on the antenna sensitivity and
bandwidth.


Not if a satellite map can be downloaded before the ride and has at
least some crude altitude info. Then I could ride sans GPS for long
stretches using only landmarks for orientation.


... There's a huge difference in performance between an
antenna that uses a choke ring to reduce ground reflections as on
survey receivers:
https://en.wikipedia.org/wiki/Choke_ring_antenna
and a smartphone that uses a tiny ceramic patch antenna. These
articles cover the problem quite nicely:
https://www.u-blox.com/sites/default/files/products/documents/GPS-Antenna_AppNote_%28GPS-X-08014%29.pdf?utm_source=en%2Fimages%2Fdownloads%2F Product_Docs%2FGPS_Antennas_ApplicationNote%28GPS-X-08014%29.pdf
http://www.taoglas.com/wp-content/uploads/2015/07/Internal-GPS-Active-Patch-AntennaAPN-13-8-002.B.pdf
Hmmm... probably more than you want to know. Suffice to say that the
smaller the antenna, the narrower the usable bandwidth. This is
important because small antennas work very badly with WAAS and barely
can handle the L1/L2 bands. Gain also suffers. From the Taoglas
article:
Typical peak gain for GPS patch antennas on standardized
ground planes are as follows:
25mm Patch 5 dBi
18mm Patch 2 dBi
15mm Patch 1 dBi
12mm Patch 0.5 dBi
10mm Patch -2 dBi
By comparison to what's found in a smartphone, these patch antennas
are HUGE. I can't seem to find the smartphone GPS antenna vendor, but
as I vaguely recall, the typical gain was about -8dBi with a rather
narrow view of the sky.

Anyway, back to your question... If you look at the antenna, and
assume that the receivers are all rather similar, your performance
will be almost totally dependent on the GPS antenna.


It would be ok to hack it and have an external antenna but I assume that
isn't in the cards for a regular cell phone. Some allow you to plug in
an antenna for the cell bands (a friend needs that to get coverage at
all at their home) but not for GPS.


With me that's a problem because my favorite routes are off-road. I try
to avoid raods whenever possible for many reasons. Like the one
yesterday where a driver came very close and leaned on the horn in an
attempt to push me from the lane to the side. No danger because he had
slowed down to my pace but such low-lifes with a drivers license are
annoying. And dangerous, especially when they are soused or nowadays
high on whatever.

Well, you could weaponize your bicycle to act as a deterrent.
https://www.google.com/search?q=bicycle+gun&tbm=isch


Sometimes I wonder if a concealed carry would make sense on a bike. At
least for cases where some low-life flies into a full road rage and
tries to attack. Or a montain lion wants to pounce :-)


I wore out the BB on my road bike. Again :-(
But it was 40 miles of fun (except for the road part)

Sigh. At least you wore it out and didn't break it. Out of
curiosity, what wore out? Bearings? Raceway? Seals? Mechanical
doping motor?


It suddenly developed a lot of play. Not so much side-to-side but
up-down. That is usually a sign that it's close to EOL. The challenge
will be to find a new square-taper version with the correct geometry.
Else I'd also have to buy new cranks and chain rings.

--
Regards, Joerg

http://www.analogconsultants.com/

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On Monday, March 20, 2017 at 2:04:15 PM UTC-4, Joerg wrote:
Snipped

Sometimes I wonder if a concealed carry would make sense on a bike. At
least for cases where some low-life flies into a full road rage and
tries to attack. Or a montain lion wants to pounce :-)


I wore out the BB on my road bike. Again :-(
But it was 40 miles of fun (except for the road part)


Hah, a mountain lion pounces from above and behind and would be on you before you even knew it was near you. ;)

What you need is a cage completely around your bicycle. MAybe add another wheel or two for better stability and then add a motor to help move it along. :)

Are you saying that you wore out a bottom bracket in only 40 miles of use? That's what it sounds like from what you posted.

Cheers

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On Mon, 20 Mar 2017 10:51:29 -0700, Joerg
wrote:

Nice, but its kind of tough to schlepp all this along on an MTB through
dirt and stuff.

You don't drag the computah with you. You take along a GPS and a data
logger or GPS tracker. The data logger collects the NMEA-0183 data
from the GPS. You play it back to the VisualGPS program(s) when you
get home (or in your vehicle if you bring along a laptop).
https://www.google.com/search?q=gps+data+logger&tbm=isch
The big problem is battery life. The pocket size data loggers are
designed to sample the GPS data, while you probably want continuous
data collection. You might need an external battery.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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On 3/20/2017 11:35 AM, Sir Ridesalot wrote:
On Monday, March 20, 2017 at 2:04:15 PM UTC-4, Joerg wrote:
Snipped

Sometimes I wonder if a concealed carry would make sense on a bike. At
least for cases where some low-life flies into a full road rage and
tries to attack. Or a montain lion wants to pounce :-)


I wore out the BB on my road bike. Again :-(
But it was 40 miles of fun (except for the road part)


Hah, a mountain lion pounces from above and behind and would be on you before you even knew it was near you. ;)

Yes, that's the big problem with mountain lions. You can't even use bear
spray because it'll be too late to spray. There are some predation
control devices with some efficacy but not 100%.
http://www.mountainlion.org/imagesportals/portalprotect/APHIS%20Electronic%20Guard.pdf.
Battery powered.

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On 2017-03-20 11:44, Jeff Liebermann wrote:
On Mon, 20 Mar 2017 10:51:29 -0700, Joerg
wrote:

Nice, but its kind of tough to schlepp all this along on an MTB through
dirt and stuff.

You don't drag the computah with you. You take along a GPS and a data
logger or GPS tracker.


Then back at home I can tell my wife "See, honey, this is the reason why
I became lost and had to pitch a tent out in the boonies".


The data logger collects the NMEA-0183 data
from the GPS. You play it back to the VisualGPS program(s) when you
get home (or in your vehicle if you bring along a laptop).


My MTB _is_ my vehicle, from garage all the way back to garage :-)


https://www.google.com/search?q=gps+data+logger&tbm=isch
The big problem is battery life. The pocket size data loggers are
designed to sample the GPS data, while you probably want continuous
data collection. You might need an external battery.


I just want a map to see where I am and where I could go, while on the
ride. Preferably in a way that it won't steer me into an off-limits
quarry, a rancher with a shotgun, or something like that.

--
Regards, Joerg

http://www.analogconsultants.com/

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On 2017-03-20 11:35, Sir Ridesalot wrote:
On Monday, March 20, 2017 at 2:04:15 PM UTC-4, Joerg wrote: Snipped

Sometimes I wonder if a concealed carry would make sense on a bike.
At least for cases where some low-life flies into a full road rage
and tries to attack. Or a montain lion wants to pounce :-)


I wore out the BB on my road bike. Again :-( But it was 40
miles of fun (except for the road part)


Hah, a mountain lion pounces from above and behind and would be on
you before you even knew it was near you. ;)

What you need is a cage completely around your bicycle. MAybe add
another wheel or two for better stability and then add a motor to
help move it along. :)

Are you saying that you wore out a bottom bracket in only 40 miles of
use? That's what it sounds like from what you posted.


No, it just happened on that ride. RRRT .. RRRT .. now what the heck is
that? Looked down, chain rings sloshes left to right. This one lasted
probably around 10k miles. Not great but still better than 3-4k in my
student days. I guess that (plus spokes, rear tires, cassettes and
chains) is the price to pay for living in the hills. Yesterday I popped
a spoke. Again.

The bottom bracket has to limp along for a while until I have time to
fix my MTB where I wore out stuff at its rear end. Can't be without a
(at least somewhat) working bike.

--
Regards, Joerg

http://www.analogconsultants.com/

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On Mon, 20 Mar 2017 08:48:02 -0700, Jeff Liebermann
wrote:

On Mon, 20 Mar 2017 18:33:51 +0700, John B.
wrote:
Way back when, I went to considerable effort to learn proper
navigation. Sextant, HO tables and lessons from the lead navigator in
a B-52 squadron. What sort of took the shine off the effort was when I
did the usual three shot position and got a "cocked hat"that was about
a mile and a half on each side. When I told the Major about it he
commented that I was doing real good. I replied that I didn't think
that a triangle that was a mile and a half on each side wasn't very
accurate he assured me that it was "pretty good for celestial
navigation.... which is why we don't use that for the B-52's" :-)

Accurate navigation with an aviation sextant is far more difficult
than marine navigation. If you were doing celestial or lunar
navigation on the ground, using an averaging bubble sextant artificial
horizon, I would say 1.5 miles was doing very good. If you were doing
it while flying, amazingly good.

It was with a common, ordinary, sextant and the shots were taken from
shore using the ocean as the horizon. From a known height above the
water :-)

the rest deleted
--
Cheers,

John B.