Spoke sensor for bicycle...

[Don Y]

On 6/14/2022 8:51 AM, Dimiter_Popoff wrote:

I started cycling again (used to as a kid...) some 4 years ago.
And while I know there are plenty of super cheap \"bicycle computers\"
I have been thinking of making my own.

As the COTS units are \"super cheap\", one has to assume you want
to do something MORE -- or differently...

Thus so far 4 years no speed/mileage indicator for me, obviously.
While this may likely remain the case forever I am still thinking
about it - not the obvious things like the MCU, display etc., just
the rotation sensor. They all use a magnet placed somewhere on one
of the wheels and some sensor, I have used a Hall sensor for
pretty precise positioning of the rotor of our TLD reader etc.,
but I only still keep on thinking of making the thing because I
imagine it sensing just the spokes, i.e. making some inductive sensor.

You need to consider your goal. If you simply want to know your
\"physical displacement\" on the globe, then periodic fixes from a GPS
(with straightline interpolation of route traveled) is a crude
approximation. Advantage: you likely are already carrying a cell
phone that could give you that data. Disadvantage: GPS accuracy
varies (from moment to moment) as does reception. Likely won\'t
tell you you\'re moving at all if your pedaling in a tight circle!

A variable reluctance sensor noting the passing of one or more
\"slugs\" on the wheel gives you an idea of rotation -- if you
aren\'t concerned with direction of rotation (software to filter out
\"jitter\" if you\'re stopped and rocking forwards and backwards on
a \"sense point\"). A magnet and reed switch can do comparable.

Optical ON THE WHEEL is likely not practical due to weather
conditions.

All of these have issues with proximity of sensor -- an out of
true wheel (wobble) could complicate things.

Personally, if I saw some added value to rolling my own, I\'d
opt for a \"vintage\" speedometer\'s pickup:

<https://i.ebayimg.com/images/g/JkMAAOSws21iGSc9/s-l1600.jpg>

transferring motion through a \"cable-in-cable\" to a \"head
unit\" that has been gutted. Mount a toothed gear on the end
of the cable shaft *in* the head unit and sense rotation optically
or variable reluctance. Quadrature detector if you want to
be able to note direction of movement for FINE sensitivity.

Electronics mounted on a little board that also supports the
inductive/optical sensors -- display, controls, etc.

This lets you move the electronics (and display) away
from the wheel -- which is likely kicking up mud, water, etc.

I know what I will try out etc., I may even get to designing one before
the millennium is over but well, these thoughts seem to be on topic and
I am sure there are people with more experience making inductive
sensors than I have.

 

[Lasse Langwadt Christensen]

tirsdag den 14. juni 2022 kl. 21.21.00 UTC+2 skrev Don Y:

On 6/14/2022 8:51 AM, Dimiter_Popoff wrote:
I started cycling again (used to as a kid...) some 4 years ago.
And while I know there are plenty of super cheap \"bicycle computers\"
I have been thinking of making my own.
As the COTS units are \"super cheap\", one has to assume you want
to do something MORE -- or differently...
Thus so far 4 years no speed/mileage indicator for me, obviously.
While this may likely remain the case forever I am still thinking
about it - not the obvious things like the MCU, display etc., just
the rotation sensor. They all use a magnet placed somewhere on one
of the wheels and some sensor, I have used a Hall sensor for
pretty precise positioning of the rotor of our TLD reader etc.,
but I only still keep on thinking of making the thing because I
imagine it sensing just the spokes, i.e. making some inductive sensor.
You need to consider your goal. If you simply want to know your
\"physical displacement\" on the globe, then periodic fixes from a GPS
(with straightline interpolation of route traveled) is a crude
approximation. Advantage: you likely are already carrying a cell
phone that could give you that data. Disadvantage: GPS accuracy
varies (from moment to moment) as does reception. Likely won\'t
tell you you\'re moving at all if your pedaling in a tight circle!

A variable reluctance sensor noting the passing of one or more
\"slugs\" on the wheel gives you an idea of rotation -- if you
aren\'t concerned with direction of rotation (software to filter out
\"jitter\" if you\'re stopped and rocking forwards and backwards on
a \"sense point\"). A magnet and reed switch can do comparable.

Optical ON THE WHEEL is likely not practical due to weather
conditions.

All of these have issues with proximity of sensor -- an out of
true wheel (wobble) could complicate things.

Personally, if I saw some added value to rolling my own, I\'d
opt for a \"vintage\" speedometer\'s pickup:

https://i.ebayimg.com/images/g/JkMAAOSws21iGSc9/s-l1600.jpg

transferring motion through a \"cable-in-cable\" to a \"head
unit\" that has been gutted. Mount a toothed gear on the end
of the cable shaft *in* the head unit and sense rotation optically
or variable reluctance. Quadrature detector if you want to
be able to note direction of movement for FINE sensitivity.

how would that make any sense compared to the simple and ultra reliable reed and magnet?

Rube Goldberg would be proud

 

[Don Y]

On 6/14/2022 12:39 PM, Lasse Langwadt Christensen wrote:

tirsdag den 14. juni 2022 kl. 21.21.00 UTC+2 skrev Don Y:
On 6/14/2022 8:51 AM, Dimiter_Popoff wrote:
I started cycling again (used to as a kid...) some 4 years ago.
And while I know there are plenty of super cheap \"bicycle computers\"
I have been thinking of making my own.
As the COTS units are \"super cheap\", one has to assume you want
to do something MORE -- or differently...
Thus so far 4 years no speed/mileage indicator for me, obviously.
While this may likely remain the case forever I am still thinking
about it - not the obvious things like the MCU, display etc., just
the rotation sensor. They all use a magnet placed somewhere on one
of the wheels and some sensor, I have used a Hall sensor for
pretty precise positioning of the rotor of our TLD reader etc.,
but I only still keep on thinking of making the thing because I
imagine it sensing just the spokes, i.e. making some inductive sensor.
You need to consider your goal. If you simply want to know your
\"physical displacement\" on the globe, then periodic fixes from a GPS
(with straightline interpolation of route traveled) is a crude
approximation. Advantage: you likely are already carrying a cell
phone that could give you that data. Disadvantage: GPS accuracy
varies (from moment to moment) as does reception. Likely won\'t
tell you you\'re moving at all if your pedaling in a tight circle!

A variable reluctance sensor noting the passing of one or more
\"slugs\" on the wheel gives you an idea of rotation -- if you
aren\'t concerned with direction of rotation (software to filter out
\"jitter\" if you\'re stopped and rocking forwards and backwards on
a \"sense point\"). A magnet and reed switch can do comparable.

Optical ON THE WHEEL is likely not practical due to weather
conditions.

All of these have issues with proximity of sensor -- an out of
true wheel (wobble) could complicate things.

Personally, if I saw some added value to rolling my own, I\'d
opt for a \"vintage\" speedometer\'s pickup:

https://i.ebayimg.com/images/g/JkMAAOSws21iGSc9/s-l1600.jpg

transferring motion through a \"cable-in-cable\" to a \"head
unit\" that has been gutted. Mount a toothed gear on the end
of the cable shaft *in* the head unit and sense rotation optically
or variable reluctance. Quadrature detector if you want to
be able to note direction of movement for FINE sensitivity.

how would that make any sense compared to the simple and ultra reliable reed and magnet?

\"As the COTS units are \"super cheap\", one has to assume you want
to do something MORE -- or differently...\"

He can *buy* the \"ultrareliable reed switch and magnet\". Presumably,
that doesn\'t meet his needs. It doesn\'t, for example, register correctly
if the magnet happens to be CLOSE (rotationally) to the switch and
you are stopped -- chatting with someone -- while rocking forwards and
backwards with the bicycle. (it has no sense of direction)

It doesn\'t register variations in speed within a single revolution
(e.g., cranking up hill) or the instantaneous WHEEL acceleration from
the rider\'s efforts.

It also requires the wheel to be true (no wobble) to ensure the distance
from magnet to switch is sufficient to reliably engage -- while not getting
*whacked* by some other portion of the wheel as it passes that isn\'t
true.

The magnet can be dislodged, sensor alignment botched, etc. If
you swap out the wheel, you have to remount a new magnet on the
replacement wheel, ensure proper alignment, etc.

And, you\'re still going to have to run a (electrical) cable up
to some sort of display/control unit. And, protect that input
to the electronics (i.e., you wouldn\'t want to directly expose a
pin to that external signal) lest the device die with the first
bit of ESD.

Instead, bring the motion (ALL of it) up to that unit and let *it* decide
what criteria are appropriate to measure. Instead of cable-in-cable plugging
into the back of a legacy \"speedometer\" (indicator), let it drive a slotted
wheel/gear mounted on a board already aligned with the sensors (which need
not worry about the same environmental issues that sensing ON the wheel
imposes) and UNBUFFERED inputs to whatever processing/display/control logic.

> Rube Goldberg would be proud

Most of his designs worked!

 

[amdx]

On 6/14/2022 12:35 PM, Dimiter_Popoff wrote:

On 6/14/2022 20:25, Ricky wrote:
On Tuesday, June 14, 2022 at 1:16:34 PM UTC-4, John Doe wrote:
Dimiter_Popoff <d...@tgi-sci.com> wrote:

I started cycling again (used to as a kid...) some 4 years ago. And
while I know there are plenty of super cheap \"bicycle computers\" I
have
been thinking of making my own. Thus so far 4 years no speed/mileage
indicator for me, obviously. While this may likely remain the case
forever I am still thinking about it - not the obvious things like the
MCU, display etc., just the rotation sensor. They all use a magnet
placed somewhere on one of the wheels and some sensor, I have used a
Hall sensor for pretty precise positioning of the rotor of our TLD
reader etc., but I only still keep on thinking of making the thing
because I imagine it sensing just the spokes, i.e. making some
inductive
sensor.

I know what I will try out etc., I may even get to designing one
before
the millennium is over but well, these thoughts seem to be on topic
and
I am sure there are people with more experience making inductive
sensors
than I have.
This might be blasphemy, but...

Speed and mileage indication is easily done with a smartphone these
days,
at least here in America.

People often talk about cell phones as if they had universal
coverage.  That is true for 99.9% of where people spend their time. 
But that 0.1% of the time, like biking in the woods, you are out of
cell phone range.  So any solution needs to not depend on a cell
phone connection.  If you can use the GPS in your phone without a
cell connection, great!  But I haven\'t found such a program as yet. 
Maybe I just haven\'t dug deep enough.


Oh where I bike there is coverage allright, and I think I had seen
references to some apps for biking. Looks like the only thing making
me think of that \"project\" I am unlikely to ever even start is the
sensor design.... (I am vague because I am not so sure myself why I
keep thinking of this every now and then for 4 years and still have
nothing in use when I bike .

Google tracks me all over, it knows if I drive, bike or walk. I\'m not
sure the times that has come in handy is worth being tracked.
But at least if a bank is robbed my phone should be able to prove it
didn\'t do it.

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

 

[John Doe]

Okay then, just clip a playing card to the fork.

 

[whit3rd]

On Tuesday, June 14, 2022 at 12:40:03 PM UTC-7, lang...@fonz.dk wrote:

tirsdag den 14. juni 2022 kl. 21.21.00 UTC+2 skrev Don Y:

Personally, if I saw some added value to rolling my own, I\'d
opt for a \"vintage\" speedometer\'s pickup:

https://i.ebayimg.com/images/g/JkMAAOSws21iGSc9/s-l1600.jpg

transferring motion through a \"cable-in-cable\" to a \"head
unit\" that has been gutted. Mount a toothed gear on the end
of the cable shaft *in* the head unit and sense rotation optically
or variable reluctance. Quadrature detector if you want to
be able to note direction of movement for FINE sensitivity.
how would that make any sense compared to the simple and ultra reliable reed and magnet?

Rube Goldberg would be proud

Two advantages: it knows forward from reverse, and it has angular sensitivity to sub-one-revolution
movement. It also doesn\'t need an adjustment-type mount for the sensor, just
slap it around the axle and mount the wheel. There\'s nothing to prevent that kind
of axle-mount item from having a magnet and quadrature reed switches, of course; the speedometer-cable
is a bit of a hassle compared to a signal wire.

A better solution would be to instument a hub and axle, but the axle diameter is fixed by the bicycle frame, and
the hub by the wheel-builders. That means redesigns of the mechanical bits unless one lucks out and
finds a compatible generator hub off-the-shelf.

 

[Joe Gwinn]

On Tue, 14 Jun 2022 20:09:26 +0300, Dimiter_Popoff <dp@tgi-sci.com>
wrote:

On 6/14/2022 18:57, Joe Gwinn wrote:
On Tue, 14 Jun 2022 18:51:21 +0300, Dimiter_Popoff <dp@tgi-sci.com
wrote:

I started cycling again (used to as a kid...) some 4 years ago.
And while I know there are plenty of super cheap \"bicycle computers\"
I have been thinking of making my own.
Thus so far 4 years no speed/mileage indicator for me, obviously.
While this may likely remain the case forever I am still thinking
about it - not the obvious things like the MCU, display etc., just
the rotation sensor. They all use a magnet placed somewhere on one
of the wheels and some sensor, I have used a Hall sensor for
pretty precise positioning of the rotor of our TLD reader etc.,
but I only still keep on thinking of making the thing because I
imagine it sensing just the spokes, i.e. making some inductive sensor.

I know what I will try out etc., I may even get to designing one before
the millennium is over but well, these thoughts seem to be on topic and
I am sure there are people with more experience making inductive
sensors than I have.


.<https://en.wikipedia.org/wiki/Variable_reluctance_sensor


Joe Gwinn

Hmmm, but will that work at really low speed (like when pushing the
bike uphill)? It is an idea to do it this way (I did not even know the
name of the method so the idea is more than welcome), yet what I was
thinking was more in the line of changing some oscillation frequency
(thus detecting the spokes also \"at DC\").

Well, there is also Wiegand-wire sensors:

..<https://en.wikipedia.org/wiki/Wiegand_effect>

..<https://en.wikipedia.org/wiki/Wiegand_Sensor>

But as others have noted, the spokes may be non-magnetic. This can be
solved by adding a bit of zinc-plated mild steel tubing (automotive
brake line) glued to at least one spoke with a silicon rubber
adhesive. The spoke would pass through an inch of tube, with silicon
rubber filling the gap between tube and spoke.

Joe Gwinn

 

[server]

Dimiter_Popoff <dp@tgi-sci.com> wrote in
news:t8aapr$ab6$1@dont-email.me:

I started cycling again (used to as a kid...) some 4 years ago.
And while I know there are plenty of super cheap \"bicycle
computers\" I have been thinking of making my own.
Thus so far 4 years no speed/mileage indicator for me, obviously.
While this may likely remain the case forever I am still thinking
about it - not the obvious things like the MCU, display etc., just
the rotation sensor. They all use a magnet placed somewhere on one
of the wheels and some sensor, I have used a Hall sensor for
pretty precise positioning of the rotor of our TLD reader etc.,
but I only still keep on thinking of making the thing because I
imagine it sensing just the spokes, i.e. making some inductive
sensor.

I know what I will try out etc., I may even get to designing one
before the millennium is over but well, these thoughts seem to be
on topic and I am sure there are people with more experience
making inductive sensors than I have.

Most out there do not sense every spoke, but instead sense a metal
flag attached to one spoke and most use a hall effect sensor
transducer for that.

 

[server]

John Dope <always.look@message.header> wrote in
news:t8afpb$t21$6@dont-email.me:

Dimiter_Popoff <dp@tgi-sci.com> wrote:

I started cycling again (used to as a kid...) some 4 years ago.
And while I know there are plenty of super cheap \"bicycle
computers\" I have been thinking of making my own. Thus so far 4
years no speed/mileage indicator for me, obviously. While this
may likely remain the case forever I am still thinking about it -
not the obvious things like the MCU, display etc., just the
rotation sensor. They all use a magnet placed somewhere on one of
the wheels and some sensor, I have used a Hall sensor for pretty
precise positioning of the rotor of our TLD reader etc., but I
only still keep on thinking of making the thing because I imagine
it sensing just the spokes, i.e. making some inductive sensor.

I know what I will try out etc., I may even get to designing one
before the millennium is over but well, these thoughts seem to be
on topic and I am sure there are people with more experience
making inductive sensors than I have.

This might be blasphemy, but...

Speed and mileage indication is easily done with a smartphone
these days, at least here in America.

With a range of error. At least unless you are using militsry grade
hardware and getting military grade resolves logged.

Phones are slow at keeping up. Use one riding a bus and you can
watch the lags in real time.

Johnny loses the phone on a bus gps test! Ehhhh!

 

[John Doe]

Record-setting gas prices every day.

Highest inflation rate since 1981 when Ronald Reagan entered office.



DecadentLinuxUserNumeroUno@decadence.org wrote:

John Dope <always.look@message.header> wrote in
news:t8afpb$t21$6@dont-email.me:

Dimiter_Popoff <dp@tgi-sci.com> wrote:

I started cycling again (used to as a kid...) some 4 years ago.
And while I know there are plenty of super cheap \"bicycle
computers\" I have been thinking of making my own. Thus so far 4
years no speed/mileage indicator for me, obviously. While this
may likely remain the case forever I am still thinking about it -
not the obvious things like the MCU, display etc., just the
rotation sensor. They all use a magnet placed somewhere on one of
the wheels and some sensor, I have used a Hall sensor for pretty
precise positioning of the rotor of our TLD reader etc., but I
only still keep on thinking of making the thing because I imagine
it sensing just the spokes, i.e. making some inductive sensor.

I know what I will try out etc., I may even get to designing one
before the millennium is over but well, these thoughts seem to be
on topic and I am sure there are people with more experience
making inductive sensors than I have.

This might be blasphemy, but...

Speed and mileage indication is easily done with a smartphone
these days, at least here in America.


With a range of error. At least unless you are using militsry grade
hardware and getting military grade resolves logged.

Phones are slow at keeping up. Use one riding a bus and you can
watch the lags in real time.

Johnny loses the phone on a bus gps test! Ehhhh!

 

[server]

John Dope <always.look@message.header> wrote in news:t8b1a0$h8t$1
@dont-email.me:

Record-setting gas prices every day.

You forgot to mention record setting profits for oil companies AND
for the local gas stations, as they all jumped onto Trump\'s jack the
price to make Biden look bad bandwagon. You ain\'t fooling anyone,
you retarded fucks.

Highest inflation rate since 1981 when Ronald Reagan entered
office.

The fault also of the oil companies as the food prices, etc. all
have logistical ties to fuel prices via the transportation industry
that distributes the end products.

You dopey Republitard idiots always conveniently ignore the factors
driving inflation that besets a new administration, especially if the
other party of previous admin is a bunch of vindictive idiots not
caring about the nation as they take their jabs at the other party.

Another reason why the likes of Perry should never hold a public
office.

You could not be more stupid if you tried.

 

[John Doe]

Record-setting gas prices every day.

Highest inflation rate since 1981 when Ronald Reagan entered
office.

The stock market is down to below when Joe Biden entered office.

Biden\'s approval rating is falling to new lows.



DecadentLinuxUserNumeroUno@decadence.org wrote:

John Dope <always.look@message.header> wrote in news:t8b1a0$h8t$1
@dont-email.me:


Record-setting gas prices every day.

You forgot to mention record setting profits for oil companies AND
for the local gas stations, as they all jumped onto Trump\'s jack the
price to make Biden look bad bandwagon. You ain\'t fooling anyone,
you retarded fucks.

Highest inflation rate since 1981 when Ronald Reagan entered
office.

The fault also of the oil companies as the food prices, etc. all
have logistical ties to fuel prices via the transportation industry
that distributes the end products.

You dopey Republitard idiots always conveniently ignore the factors
driving inflation that besets a new administration, especially if the
other party of previous admin is a bunch of vindictive idiots not
caring about the nation as they take their jabs at the other party.

Another reason why the likes of Perry should never hold a public
office.

You could not be more stupid if you tried.

 

[Don Y]

On 6/14/2022 1:39 PM, whit3rd wrote:

On Tuesday, June 14, 2022 at 12:40:03 PM UTC-7, lang...@fonz.dk wrote:
tirsdag den 14. juni 2022 kl. 21.21.00 UTC+2 skrev Don Y:

Personally, if I saw some added value to rolling my own, I\'d
opt for a \"vintage\" speedometer\'s pickup:

https://i.ebayimg.com/images/g/JkMAAOSws21iGSc9/s-l1600.jpg

transferring motion through a \"cable-in-cable\" to a \"head
unit\" that has been gutted. Mount a toothed gear on the end
of the cable shaft *in* the head unit and sense rotation optically
or variable reluctance. Quadrature detector if you want to
be able to note direction of movement for FINE sensitivity.
how would that make any sense compared to the simple and ultra reliable reed and magnet?

Rube Goldberg would be proud

Two advantages: it knows forward from reverse, and it has angular sensitivity to sub-one-revolution
movement. It also doesn\'t need an adjustment-type mount for the sensor, just
slap it around the axle and mount the wheel. There\'s nothing to prevent that kind
of axle-mount item from having a magnet and quadrature reed switches, of course; the speedometer-cable
is a bit of a hassle compared to a signal wire.

A better solution would be to instument a hub and axle, but the axle diameter is fixed by the bicycle frame, and
the hub by the wheel-builders. That means redesigns of the mechanical bits unless one lucks out and
finds a compatible generator hub off-the-shelf.

The biggest win is it gets you away from the wheel. E.g., you could affix a
bar magnet to the end of the cable-in-cable and detect it\'s rotation (to
whatever extent you desire) as well as using its motion to generate *power*
for the circuit (esp with the ultra low power technologies now available;
think about the tire-rubbing generators that used to power headlamps...)

 

[whit3rd]

On Tuesday, June 14, 2022 at 5:22:18 PM UTC-7, Don Y wrote:

On 6/14/2022 1:39 PM, whit3rd wrote:

A better solution would be to instument a hub and axle, but the axle diameter is fixed by the bicycle frame, and
the hub by the wheel-builders. That means redesigns of the mechanical bits unless one lucks out and
finds a compatible generator hub off-the-shelf.

The biggest win is it gets you away from the wheel. E.g., you could affix a
bar magnet to the end of the cable-in-cable and detect it\'s rotation (to
whatever extent you desire) as well as using its motion to generate *power*
for the circuit (esp with the ultra low power technologies now available;
think about the tire-rubbing generators that used to power headlamps...)

Yeah; those delivered 2 or 3 watts; enough for a halogen flashlight lamp,
and to charge a 6V lead/acid battery for standstill lighting. If you use
one built into a wheel hub, the dynamo pole count determines the AC cycles per mile travelled.
The friction type can be precalibrated easily (the drive drum circumference is better known
than the tire\'s) if it engages the tread rather than the sidewall of the tire.

 

[rbowman]

On 06/14/2022 12:00 PM, Dimiter_Popoff wrote:

On 6/14/2022 20:43, Jan Panteltje wrote:
On a sunny day (Tue, 14 Jun 2022 18:51:21 +0300) it happened
Dimiter_Popoff
dp@tgi-sci.com> wrote in <t8aapr$ab6$1@dont-email.me>:

I started cycling again (used to as a kid...) some 4 years ago.
And while I know there are plenty of super cheap \"bicycle computers\"
I have been thinking of making my own.
Thus so far 4 years no speed/mileage indicator for me, obviously.
While this may likely remain the case forever I am still thinking
about it - not the obvious things like the MCU, display etc., just
the rotation sensor. They all use a magnet placed somewhere on one
of the wheels and some sensor, I have used a Hall sensor for
pretty precise positioning of the rotor of our TLD reader etc.,
but I only still keep on thinking of making the thing because I
imagine it sensing just the spokes, i.e. making some inductive sensor.

I know what I will try out etc., I may even get to designing one before
the millennium is over but well, these thoughts seem to be on topic and
I am sure there are people with more experience making inductive
sensors than I have.

Or you could make something like my gm_pic2:
http://panteltje.com/panteltje/pic/gm_pic2/

It uses GPS and writes to SDcard or EEPROM where you were at any time,
logs radiation there too
There is software to replay the trip on google maps.
After all the GPS talk here ..
Simple maaz using the space and time between data points will allow
you to find speed and distances.
A GPS module and a Microchip 18F14k22 + EEPROM is all you need.
Oh and a battery...
Now been working 24/7 for 8 years... As clock mostly.
No tinkering with your bike needed.
Also logs trips per bus or train.



Is the GPS accuracy/latency of the speed measurement close to that of
a car\'s speed indicator?

Most of the time. The 14\" studded tires I run in the winter have a
smaller rolling diameter than the 15\" tires the speedometer is
calibrated for so it\'s off by about 5mph. For that reason I\'m in the
habit of looking at the Nuvi speed rather than the speedometer.

In some weather conditions or when I\'m driving at the base of a ridge
that blocks the southern sky the GPS is wildly inaccurate so much so it
is easy to detect when it\'s having issues.

I often carry a GPSr when I\'m hiking (Garmin Etex 20). The terrain is
mountainous here so satellite coverage can be sketchy. Sometimes the
distance is radically off as is the maximum speed. Unless I just rolled
down a slope I\'m probably not hitting 4.7 mph. I don\'t think the device
has the intelligence to discard obvious false data points.

I\'ve got one of the step apps on the phone. It says it does not use the
GPS so it\'s working off the accelerometer data and it\'s surprisingly
accurate for the mileage particularly considering there was no setup for
the length of my stride.

 

[rbowman]

On 06/14/2022 12:44 PM, Lasse Langwadt Christensen wrote:

tirsdag den 14. juni 2022 kl. 20.00.52 UTC+2 skrev Dimiter Popoff:
On 6/14/2022 20:43, Jan Panteltje wrote:
On a sunny day (Tue, 14 Jun 2022 18:51:21 +0300) it happened Dimiter_Popoff
d...@tgi-sci.com> wrote in <t8aapr$ab6$1...@dont-email.me>:

I started cycling again (used to as a kid...) some 4 years ago.
And while I know there are plenty of super cheap \"bicycle computers\"
I have been thinking of making my own.
Thus so far 4 years no speed/mileage indicator for me, obviously.
While this may likely remain the case forever I am still thinking
about it - not the obvious things like the MCU, display etc., just
the rotation sensor. They all use a magnet placed somewhere on one
of the wheels and some sensor, I have used a Hall sensor for
pretty precise positioning of the rotor of our TLD reader etc.,
but I only still keep on thinking of making the thing because I
imagine it sensing just the spokes, i.e. making some inductive sensor.

I know what I will try out etc., I may even get to designing one before
the millennium is over but well, these thoughts seem to be on topic and
I am sure there are people with more experience making inductive
sensors than I have.

Or you could make something like my gm_pic2:
http://panteltje.com/panteltje/pic/gm_pic2/

It uses GPS and writes to SDcard or EEPROM where you were at any time, logs radiation there too
There is software to replay the trip on google maps.
After all the GPS talk here ..
Simple maaz using the space and time between data points will allow you to find speed and distances.
A GPS module and a Microchip 18F14k22 + EEPROM is all you need.
Oh and a battery...
Now been working 24/7 for 8 years... As clock mostly.
No tinkering with your bike needed.
Also logs trips per bus or train.


Is the GPS accuracy/latency of the speed measurement close to that of
a car\'s speed indicator?

a car speedometer is only required to be -0 to +10%

And for most Japanese motorcycles it is +10%. The conventional wisdom is
it\'s a liability thing. Since they can\'t control aftermarket tires they
overstate the speed. You get used to subtracting 5 mph from the reading.

 

[rbowman]

On 06/14/2022 01:01 PM, Dimiter_Popoff wrote:

On 6/14/2022 21:21, whit3rd wrote:
On Tuesday, June 14, 2022 at 8:51:30 AM UTC-7, Dimiter Popoff wrote:
I started cycling again (used to as a kid...) some 4 years ago.
And while I know there are plenty of super cheap \"bicycle computers\"
I have been thinking of making my own.
...use a magnet placed somewhere on one
of the wheels and some sensor, ... I
imagine it sensing just the spokes, i.e. making some inductive sensor.

A magnet secured to a spoke, and a reed switch, makes a durable
sensor, but
is somewhat clumsy. A sensor of the metal spoke is hard, because spokes
aren\'t all magnetic, there\'s stainless steels.

Aaaah, the stainless steel is a game changer of course. Had not thought
of that at all - though I know the spokes are not rusty (some at the end
where they are tightened to the wheel but not all and not much). And it
is not like they have not seen water, 1-2 months ago getting back
after waiting for a torrential rain to subside I was nearly in submarine
mode ...

Carbon fiber spokes would be a problem too. The LCD odometer on my
motorcycle is old and is only legible if the temperature is close to 90
F so I adapted a bike speedometer/odometer. I epoxied the magnet on the
rim near the tire bead and built a bracket for the sensor. It works
quite well and since I can program in the rolling diameter of the front
wheel it is very accurate.

 

[rbowman]

On 06/14/2022 12:24 PM, Joerg wrote:

On 6/14/22 10:16 AM, John Doe wrote:
Dimiter_Popoff <dp@tgi-sci.com> wrote:

I started cycling again (used to as a kid...) some 4 years ago. And
while I know there are plenty of super cheap \"bicycle computers\" I have
been thinking of making my own. Thus so far 4 years no speed/mileage
indicator for me, obviously. While this may likely remain the case
forever I am still thinking about it - not the obvious things like the
MCU, display etc., just the rotation sensor. They all use a magnet
placed somewhere on one of the wheels and some sensor, I have used a
Hall sensor for pretty precise positioning of the rotor of our TLD
reader etc., but I only still keep on thinking of making the thing
because I imagine it sensing just the spokes, i.e. making some inductive
sensor.

I know what I will try out etc., I may even get to designing one before
the millennium is over but well, these thoughts seem to be on topic and
I am sure there are people with more experience making inductive sensors
than I have.

This might be blasphemy, but...

Speed and mileage indication is easily done with a smartphone these days,
at least here in America.


Then, later in the afternoon during an all-day ride, there will be a low
battery warning, followed by a dark screen.

Why do we always have to make things so complicated? When I grew up
speedometers didn\'t even need any electrical power. They just worked.

They just worked until the core of the flexible shaft broke. If you were
lucky the strands didn\'t tear up the housing so you could buy a new
core, figure out how long it had to be, cut if off, and crimp on the
square drive end. If you were really lucky the transmission end of the
drive was above the lubricant level so you didn\'t have Type F fluid
running down your arm.

While I can get nostalgic for the good old days I\'m not senile enough to
forget what a pain in the butt it was when things just didn\'t work.

 

[rbowman]

On 06/14/2022 06:22 PM, Don Y wrote:

The biggest win is it gets you away from the wheel. E.g., you could
affix a
bar magnet to the end of the cable-in-cable and detect it\'s rotation (to
whatever extent you desire) as well as using its motion to generate *power*
for the circuit (esp with the ultra low power technologies now available;
think about the tire-rubbing generators that used to power headlamps...)

What a wondrous invention they were... All that aggro for a one
candlepower headlamp. Somehow I associate those with the Sturmey-Archer
three speed hubs.

I suppose driving a generator that way is better than driving the
bicycle with a 26cc motor in a similar way:

http://bumblebeebolton.com/front_instructions.html

I thought the concept might have been relegated to the trash bin of
history but I\'ve seen a similar design for a DIY low rent eBike.

 

[Ricky]

On Tuesday, June 14, 2022 at 2:36:47 PM UTC-4, lang...@fonz.dk wrote:

tirsdag den 14. juni 2022 kl. 20.28.02 UTC+2 skrev Ricky:
On Tuesday, June 14, 2022 at 2:00:52 PM UTC-4, Dimiter Popoff wrote:
On 6/14/2022 20:43, Jan Panteltje wrote:
On a sunny day (Tue, 14 Jun 2022 18:51:21 +0300) it happened Dimiter_Popoff
d...@tgi-sci.com> wrote in <t8aapr$ab6$1...@dont-email.me>:

I started cycling again (used to as a kid...) some 4 years ago.
And while I know there are plenty of super cheap \"bicycle computers\"
I have been thinking of making my own.
Thus so far 4 years no speed/mileage indicator for me, obviously.
While this may likely remain the case forever I am still thinking
about it - not the obvious things like the MCU, display etc., just
the rotation sensor. They all use a magnet placed somewhere on one
of the wheels and some sensor, I have used a Hall sensor for
pretty precise positioning of the rotor of our TLD reader etc.,
but I only still keep on thinking of making the thing because I
imagine it sensing just the spokes, i.e. making some inductive sensor.

I know what I will try out etc., I may even get to designing one before
the millennium is over but well, these thoughts seem to be on topic and
I am sure there are people with more experience making inductive
sensors than I have.

Or you could make something like my gm_pic2:
http://panteltje.com/panteltje/pic/gm_pic2/

It uses GPS and writes to SDcard or EEPROM where you were at any time, logs radiation there too
There is software to replay the trip on google maps.
After all the GPS talk here ..
Simple maaz using the space and time between data points will allow you to find speed and distances.
A GPS module and a Microchip 18F14k22 + EEPROM is all you need.
Oh and a battery...
Now been working 24/7 for 8 years... As clock mostly.
No tinkering with your bike needed.
Also logs trips per bus or train.


Is the GPS accuracy/latency of the speed measurement close to that of
a car\'s speed indicator?
\"Close\" is probably the best you can claim. Each 1 second update is a second old by the time you get it from the GPS. The accuracy can be there, but it depends on the constellation. With some xx feet of accuracy, each calculation can have errors that are significant if you are not moving fast. 30 mph is 44 fps, so 14 foot accuracy (what I\'m seeing now and a typical value) is significant. GPS measurements are typically filtered. That\'s one reason why your car navigation can prompt you rather late sometimes (or early).. It is hard for a GPS to know what lane you are in, but can tell if you are on the parallel access road and not the main highway.

https://www.gps.gov/systems/gps/performance/accuracy/

\"This measure must be combined with other factors outside the government\'s control, including satellite geometry, signal blockage, atmospheric conditions, and receiver design features/quality, to calculate a particular receiver\'s speed accuracy.\"

--

Rick C.

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