Op zondag 30 juli 2017 03:01:10 UTC+2 schreef jbeattie:
On Saturday, July 29, 2017 at 10:44:08 AM UTC-7, AMuzi wrote:
On 7/29/2017 11:34 AM, Joerg wrote:
On 2017-07-29 09:16, AMuzi wrote:
On 7/29/2017 10:19 AM, Graham wrote:

"Joerg" wrote in message
...
On 2017-07-29 02:14, Graham wrote:

"Joerg" wrote in message
...
Had to change the battery again on my Bell Dashboard
100 cycling
speedometer. Or what they call "cycle computer" In the
manual it
says one can re-enter the odometer reading but nowhere
it says how.
When I contacted Bell years ago they said "no, you
can't". Does
anyone know a secret trick Bell doesn't know?

I keep a log but it gets old having to calculate to
see when the
rear tire or other stuff is nearing end-of-life.
Mainly to avoid a
*KAPOW* surprise way out in the boonies. Many tires
don't have
TWI.

-- Regards, Joerg

http://www.analogconsultants.com/

Looking at your day job from the above link why not
just design a
circuit to replicate the job of the magnet which is
only a switch
which is creating a pulsed current/voltage read by the
head unit
electronics. Then set the tyre size to maximum and
determine the
maximum response frequency of the head unit circuitry
and simulate
pulses at that frequency. If the frequency is
reasonably high it
should not take too long to reset the mileage. With a tyre
circumference of 9999mm, if it will take that, then you
are looking
at 10m per Hz.


Sure I could design a meter that works better than
commercial one.
[snip]

No you miss my point. I am not suggesting you
design/build a new unit
simply knock up a simple circuit to mimic the magnet
driven switch
opening and closing and connect it to the appropriate
terminals on the
head unit. If the unit can respond to switching rates up
to say 1kHz
then the job should be reasonably quick and could be left
to run for a
known period of time to get the mileage back to where you
want it. At
10m per switch cycle you would advance the reading
36kms/hr at 1hz so
100Hz which should be possible would give you 3600kms/hr
1KHz would
look to be ideal as it would give you 36,000kms/hr.

A bench grinder would also work with a magnet fixed to it
and the
sensor held next to it. That might take a good bit longer
depending on
the speed of the grinder.


Ah, yes, clocking it all back in by pretending a 4120mi
ride. Good idea. I could take an old printer motor, mout a
wooden disc, glue a little magent on that and strap the
whole thing into the spokes.

It would probably take days though since the speedometer
will peg somewhere. And eat a lot of the new battery's juice
which would kind of defeat the purpose.


There are sensors which can read 1720~1760rpm (grinder
speeds) but a
copper-steel reed switch is not one of them.


Reed switches would be way too expensive for such products.
It's usually just a coil. Almost has to be because it must
generate a voltage that triggers the turned-off meter
circuitry to turn on upon wheel rotation.


Except for rare exceptions (ex: defunct Avocet), almost all
bicycle computers use that type of switch to iterate wheel
or crank rpm.

I could sell him my old Avocet, and he could kludge it.

It seems to me like he could get a sharpie and write on the screen "+ [number of miles]." Problem solved. Or maybe put the number in his wallet on the back of a growler fill coupon -- or tattoo it to his forehead. Or, plan B, just look at his tires to see if they are worn -- or measure his chain. I suppose this would impede the completion of his definitive work on tire and chain wear rates by brand and model, but only for one wear cycle. A new chain or tire would have a new odometer reading. I don't think tires wear any faster if a bike has more or less cumulative miles, but I could be wrong about that. I had some high mile bikes that would just blow through tires..

-- Jay Beattie.

Simple cycling computers are so cheap he could buy a new one every time he replaces a tire or a chain......

Lou