Dodgy computer readings



D

Danny Colyer

Guest
What's likely to cause excessive readings in a corded computer
(specifically a CatEye Astrale) that's functioned without problems for
nearly 5 years?

When I got to work this morning, my computer showed a top speed of 97.3
mph. I have a high degree of confidence that this was wrong. Trip
distance showed 5.44 miles. Given that I topped up the tyres last
night, it should have been 5.36 or 5.37.

When I got home this evening it showed a top speed of 63.3 and a trip
distance of 5.64 (it's usually 5.59).

This morning I wondered if mobile phone interference could have had any
effect, as I took a call during the ride. But my phone wasn't even on
this evening.

The leads for my Lumicycles run alongside the computer lead for some of
their length, so this evening I wondered if switching my main beam on
and off during the ride may have had some effect. But it never has
before, and I didn't use the Lumis at all this morning.

I had the wheel off yesterday to fix a puncture. I often manage to
knock the computer sensor when I refit the wheel, but I'm not aware of
that happening yesterday. Anyway, that usually results in either no
reading, or in the sensor hitting the spokes. Neither has happened this
time.

I guess I'll just have a play with the sensor and see if I get similarly
strange readings next week.

--
Danny Colyer (my reply address is valid but checked infrequently)
<URL:http://www.colyer.plus.com/danny/>
Subscribe to PlusNet <URL:http://www.colyer.plus.com/referral/>
"He who dares not offend cannot be honest." - Thomas Paine
 
Danny Colyer wrote:
> What's likely to cause excessive readings in a corded computer
> (specifically a CatEye Astrale) that's functioned without problems for
> nearly 5 years?
>
> When I got to work this morning, my computer showed a top speed of
> 97.3 mph. I have a high degree of confidence that this was wrong.
> Trip distance showed 5.44 miles. Given that I topped up the tyres
> last night, it should have been 5.36 or 5.37.
>
> When I got home this evening it showed a top speed of 63.3 and a trip
> distance of 5.64 (it's usually 5.59).

I've had a Cateye give double max speed readings when the sensor has been
too close to the magnet or not quite positioned right. It must've clicked
twice per rev sometimes, but not often enough to affect trip distance very
much.

Well done for doing 48.65 mph! :)

> This morning I wondered if mobile phone interference could have had
> any effect, as I took a call during the ride. But my phone wasn't
> even on this evening.
>
> The leads for my Lumicycles run alongside the computer lead for some
> of their length, so this evening I wondered if switching my main beam
> on and off during the ride may have had some effect. But it never has
> before, and I didn't use the Lumis at all this morning.

I wouldn't have thought anything like that would affect a /corded/
computer. The sensors are just reed switches that simply close the
circuit (I guess there's a fair amount of current and it's all very
binary).

> I had the wheel off yesterday to fix a puncture. I often manage to
> knock the computer sensor when I refit the wheel, but I'm not aware of
> that happening yesterday. Anyway, that usually results in either no
> reading, or in the sensor hitting the spokes. Neither has happened
> this time.

I bet that's the problem but with a different result this time. Self
amalgamating rubber tape should keep the sensor firmly in place (and epoxy
resin for magnet).

~PB
 
I've had this problem. All I could think of is that it was caused by
the bike wheel rocking backwards and forwards slightly (on a train or
when falling over) when the magnet was near the coil.
 
Bob wrote:
> I've had this problem. All I could think of is that it was caused by
> the bike wheel rocking backwards and forwards slightly (on a train or
> when falling over) when the magnet was near the coil.

You wouldn't be able to rock it fast enough to read 97 mph if you tried,
so I'm quite sure the problem is caused by dodgy sensor/magnet
positioning. I've had exactly the same problem two or three times....
well, except the reading was lower in my cases!

~PB
 
I wrote:
> Bob wrote:
>> I've had this problem. All I could think of is that it was caused by
>> the bike wheel rocking backwards and forwards slightly (on a train or
>> when falling over) when the magnet was near the coil.
>
> You wouldn't be able to rock it fast enough to read 97 mph if you
> tried, so I'm quite sure the problem is caused by dodgy sensor/magnet
> positioning. I've had exactly the same problem two or three times....
> well, except the reading was lower in my cases!

ps. Fixed by moving the sensor further out.

~PB
 
Bob wrote:
>>I've had this problem. All I could think of is that it was caused by
>>the bike wheel rocking backwards and forwards slightly (on a train or
>>when falling over) when the magnet was near the coil.

and Pete Biggs responded:
> You wouldn't be able to rock it fast enough to read 97 mph if you tried,

It'd certainly be a challenge with the 20" wheel that my bike computer
reads. You can get close with the 36" wheel on a Coker, though :)

--
Danny Colyer (my reply address is valid but checked infrequently)
<URL:http://www.colyer.plus.com/danny/>
Subscribe to PlusNet <URL:http://www.colyer.plus.com/referral/>
"He who dares not offend cannot be honest." - Thomas Paine
 
Danny Colyer wrote:
> What's likely to cause excessive readings in a corded computer
> (specifically a CatEye Astrale) that's functioned without problems for
> nearly 5 years?


Low battery? If the battery is 5 yrs old. Or the only time I've had
problems with a Cateye corded over-reading it was caused by rain
getting in between the computer and the mount. And solved by a smear of
oil on the mounting to repel water.
Iain
 
Danny Colyer wrote:
> I had the wheel off yesterday to fix a puncture. I often manage to
> knock the computer sensor when I refit the wheel, but I'm not aware of
> that happening yesterday.

97.3mph... Hmmm... Did you inadvertently fit a second, or even a third,
sensor? I know it sounds unlikely, but you never know...

d.
 
Danny Colyer <[email protected]> wrote:
> What's likely to cause excessive readings in a corded computer
> (specifically a CatEye Astrale) that's functioned without problems for
> nearly 5 years?

Completely unlikely unless something else has changed, but Sheldon Brown
(I think) had an explanation of incorrect readings being because the
magnet orientation was wrong - read it years ago and the back of my
tiny mind says it might have been for only one type of computer, too.

--
Nobby
 
[email protected] wrote:
> Low battery? If the battery is 5 yrs old. Or the only time I've had
> problems with a Cateye corded over-reading it was caused by rain
> getting in between the computer and the mount. And solved by a smear of
> oil on the mounting to repel water.

The battery's probably 2 or 3 years old, so that's a possibility. I've
never had any problem with this computer in the rain, even in torrential
downpours.

--
Danny Colyer (my reply address is valid but checked infrequently)
<URL:http://www.colyer.plus.com/danny/>
Subscribe to PlusNet <URL:http://www.colyer.plus.com/referral/>
"He who dares not offend cannot be honest." - Thomas Paine
 
Dodgy computer readings?

There's only quality computer reading here on u.r.c.
--
Ambrose
 
In article <[email protected]>, Danny
Colyer ([email protected]) wrote:
> What's likely to cause excessive readings in a corded computer
> (specifically a CatEye Astrale) that's functioned without problems for
> nearly 5 years?
>
> When I got to work this morning, my computer showed a top speed of 97.3
> mph. I have a high degree of confidence that this was wrong. Trip
> distance showed 5.44 miles. Given that I topped up the tyres last
> night, it should have been 5.36 or 5.37.
>
> When I got home this evening it showed a top speed of 63.3 and a trip
> distance of 5.64 (it's usually 5.59).
>
> This morning I wondered if mobile phone interference could have had any
> effect, as I took a call during the ride. But my phone wasn't even on
> this evening.
>
> The leads for my Lumicycles run alongside the computer lead for some of
> their length, so this evening I wondered if switching my main beam on
> and off during the ride may have had some effect. But it never has
> before, and I didn't use the Lumis at all this morning.
>
> I had the wheel off yesterday to fix a puncture. I often manage to
> knock the computer sensor when I refit the wheel, but I'm not aware of
> that happening yesterday. Anyway, that usually results in either no
> reading, or in the sensor hitting the spokes. Neither has happened this
> time.
>
> I guess I'll just have a play with the sensor and see if I get similarly
> strange readings next week.

I had something similar not long ago which turned out to have been
caused by the insulation on the wires having gone west, allowing short
circuits and similar trumpery. I decided to investigate after Vmax
reached 224 km/h past the Imperial /Wa/ Museum.

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
Funsize Mars bars? What could possibly be MORE fun about eating LESS
chocolate?
 
Dave Larrington wrote:
> I had something similar not long ago which turned out to have been
> caused by the insulation on the wires having gone west, allowing short
> circuits and similar trumpery.


With the strange readings I sometimes get on a variety of cyclo
computers, I think that there is more than one possible cause, thus:

* mobile phone interference (possibly not yours but someone passing)
* rain/condensation inside unit
* electromagnetic interference from certain types of light

As other people have said, magnet/sensor position and wiring problems
may also cause strange behaviour.

My Raleigh Sports (3-speed Sturmey Archer hub, feels like it's made of
solid lead) apparently reached 968mph on the way to work one day. I
know I was riding hard and fast, but somehow I don't believe this to be
accurate!

My wife has a cyclo computer that used to work fine, and now goes nuts
every time she turns on the front light. It's also very tempermental
regarding time of day (it doesn't like going out after dark, for some
reason).

PhilD

--
<><
 
Dave Larrington wrote:
> I had something similar not long ago which turned out to have been
> caused by the insulation on the wires having gone west, allowing short
> circuits and similar trumpery. I decided to investigate after Vmax
> reached 224 km/h past the Imperial /Wa/ Museum.

213.7mph this morning. I tinkered with the sensor at lunchtime (didn't
get round to it over the weekend) and clocked 158.7mph this evening.

Insulation might be worth checking. Also, if I think about it tomorrow
morning, I'll leave the max speed on the display and see if it shoots up
at any particular point on the ride. The first dodgy reading coincided
with my removal of the wheel to fix a puncture, which could have
resulted in the sensor being knocked, but it also coincided with the
wiring up of several new lights-on-sticks along the road that I work on.
I dunno if a badly wired light-on-a-stick might put out a strong
enough magnetic field to screw up the computer readings of passing cyclists.

--
Danny Colyer (my reply address is valid but checked infrequently)
<URL:http://www.colyer.plus.com/danny/>
Subscribe to PlusNet <URL:http://www.colyer.plus.com/referral/>
"He who dares not offend cannot be honest." - Thomas Paine
 
Danny Colyer wrote:
.........
> I dunno if a badly wired light-on-a-stick might put out a strong
> enough magnetic field to screw up the computer readings of passing
> cyclists.

Coiled wires? My money's still on sensor alignment though.

~PB
 
Danny Colyer wrote:
> I dunno if a badly wired light-on-a-stick might put out a strong
> enough magnetic field to screw up the computer readings of passing cyclists.


Might do. Further to my previous message, going in and out of
supermarkets can have a funny effect: the security sensors to stop you
nicking electronics and expensive booze play havock, as does the
inductive loop they put in the road around retail parks to disable
trolleys. I always put my cycle computer in a tin before going into a
supermarket now.

PhilD

--
<><
 
PhilD wrote:
> Further to my previous message, going in and out of
> supermarkets can have a funny effect: the security sensors to stop you
> nicking electronics and expensive booze play havock, as does the
> inductive loop they put in the road around retail parks to disable
> trolleys. I always put my cycle computer in a tin before going into a
> supermarket now.

Is yours a wired a cordless computer?

~PB
 
Pete Biggs wrote:
> Is yours a wired a cordless computer?


Yes, and yes. I have separate computers for different bikes. I have
had problems with both sorts, seemingly by the same cause(s). I admit
though that wireless types give more spectacular erroneous readings.

PhilD

--
<><
 
I wrote:
>>I dunno if a badly wired light-on-a-stick might put out a strong
>>enough magnetic field to screw up the computer readings of passing
>>cyclists.

and Pete Biggs responded:
> Coiled wires? My money's still on sensor alignment though.

I kept an eye on the max speed this morning. It was 168.2 mph by the
time I joined the cyclepath, 3/4 mile from home and the best part of 5
miles before reaching the new lights-on-sticks.

I readjusted the sensor again at lunchtime. On the way home, I had a
reading of 160.8 mph by the time I joined the cyclepath (a few hundred
yards from the office, after the lights-on-sticks). I reset the
computer and had a more sensible max of 22 mph when I got home 5 miles
later.

I'll try cleaning the contacts this evening. If I still have problems
tomorrow then I'll try another computer (I happen to have another
Astrale), which should determine whether the problem is a low battery.

I reckon it's probably a problem with the sensor, but perhaps not with
sensor alignment, when I've still got the problem after realigning it twice.

--
Danny Colyer (my reply address is valid but checked infrequently)
<URL:http://www.colyer.plus.com/danny/>
Subscribe to PlusNet <URL:http://www.colyer.plus.com/referral/>
"He who dares not offend cannot be honest." - Thomas Paine
 
"Pete Biggs" <[email protected]> wrote in
message news:[email protected]...
>I wrote:
>> Bob wrote:
>>> I've had this problem. All I could think of is that it was caused by
>>> the bike wheel rocking backwards and forwards slightly (on a train or
>>> when falling over) when the magnet was near the coil.
>>
>> You wouldn't be able to rock it fast enough to read 97 mph if you
>> tried, so I'm quite sure the problem is caused by dodgy sensor/magnet
>> positioning. I've had exactly the same problem two or three times....
>> well, except the reading was lower in my cases!
>
> ps. Fixed by moving the sensor further out.

Don't they have trip milometers these days?

Alan

>
> ~PB
>
>
 
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