Wireless Computer Anomaly

Mark Shefrin said:

My newer Cateye wireless is showing impossibly high maximum speeds
(84 mph today). All of the other functions are stable and accurate.
The high readings happen only occasionally. While there is no lack of
interesting hypotheses from my LBS, has anyone actually seen and
solved this problem?

I doubt it'll solve it but have you replaced the battery?
---
Splat

Mark said:

My newer Cateye wireless is showing impossibly high maximum speeds (84
mph today).

My GPS once recorded a max. speed of 4032 mph on a bike ride.
Maximum readings are inherently subject to some false readings since a
single bad measurement has the capability of making such a drastic
change in the result. The GPS can sometimes get satellite signals that
have bounced off buildings or cliffs rather than taking a direct path
to the receiver. That can result in a bad position measurement and
make the unit think you travelled over a mile in the last second and
implying a very high speed.

In the case of the Cateye cyclometer which depends on noting the
number of contact closures when the spoke magnet passes the sensor it
seems most likely that there were one or more false closures recorded,
either through contact bounce or because of closures due to bumps or
vibrations rather than magnet passes. Contact bounce problems are
usually handled by the firmware in the cyclometer so there's probably
not much a customer can do to fix things. Extra closures from bumps or
vibration could be minimized by a more cushioned mounting of the sensor
- just be sure it can't move so far that the magnet no longer passes
close enough for a reliable reading.

Since it's wireless, another cause would be picking up signals from
some other device - possibly another cyclometer or heartrate monitor in
the vicinity. Have you noticed any correlation between the false
readings and having particular other cyclists nearby?

On Sat, 1 Oct 2005 20:26:18 -0400, Mark Shefrin <[email hidden]>

Quoted message said:

My newer Cateye wireless is showing impossibly high maximum speeds (84
mph today). All of the other functions are stable and accurate. The
high readings happen only occasionally. While there is no lack of
interesting hypotheses from my LBS, has anyone actually seen and solved
this problem?

I used to exeperience similar excursions. Seems it happened when I
came to a stop with the magnet in close proximity to the sensor.
Moving the sensor further from the magnet solved the problem.

Mark Shefrin said:

My newer Cateye wireless is showing impossibly high maximum speeds (84
mph today).

Is there any way I can modify my cyclocomputer to display more like
yours? I regularly practice eXtreme riding and I find that this single
metric needs some assistance before it can accurately reflect all
aspects of my unique style.

-Mike

"peter" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Since it's wireless, another cause would be picking up signals from
some other device - possibly another cyclometer or heartrate monitor in
the vicinity. Have you noticed any correlation between the false
readings and having particular other cyclists nearby?

Check your route for this one. I had problems with a heart rate monitor
giving excessively high readings every time I passed a house with an
electronic surveillance system along the fence.

--
~~~~~~~~~~~~
Jim Artherholt
[email hidden]

Sat, 1 Oct 2005 20:26:18 -0400, Mark Shefrin <[email hidden]> skrev:

Quoted message said:

My newer Cateye wireless is showing impossibly high maximum speeds (84
mph today). All of the other functions are stable and accurate. The
high readings happen only occasionally. While there is no lack of
interesting hypotheses from my LBS, has anyone actually seen and solved
this problem?

Seen, not solved. While the current speed is calculatede as an average of
several turns of the wheel (the number of which varies from one brand to
another) the max speed is calculated from only one turn of the wheel.

This means that if the mehcanical registration of the movable part inside
sensor for some reason, f.ex. bounsing, is delayed for at split second,
the interval to the next on time registration will be shorter, and the max
speed is therefore presented falsely high..

Therefore you will often experience, that the max speed is a bit above the
current speed that was displayed when you were riding the fastest.

I have two computers of different make on my bike, and they disagree a
little on everything and a lot on the question of max speed.

What could be done is to program the computers to store the highest
presented current speed at the max speed.

But never mind. Even if the max speed was correct, it wouldn't be usefull
- and not much fun either.

Ivar of Denmark

Thanks to all of you who responded. Upon further inspection, I found
that the sender on the fork had become very slightly loose. This was
likely causing the anamoly as it hasn't happened since. So I'm setting
aside all of the way more interesting radio frequency interference
hypotheses for the time being.
Best wishes, Mark

In article <2005100705490416807%mshefrin@yahoocom>,

Mark Shefrin said:

Thanks to all of you who responded. Upon further inspection, I found
that the sender on the fork had become very slightly loose. This was
likely causing the anamoly as it hasn't happened since. So I'm setting
aside all of the way more interesting radio frequency interference
hypotheses for the time being.
Best wishes, Mark

This one goes into the diagnostic data base. A loosely
attached sensor unit can send anomalous signals.

I surmise that this will be as true for wired units as
wireless units, because the probable cause of the
anomalous signal is closure of the sensor leaf switch from
mechanical shock.

--
Michael Press