Yet Another Cycling Forum
General Category => On The Road => Topic started by: Greenbank on 24 April, 2008, 09:09:44 am
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Up to April my commute in was 11.6km (+/- 0.2km). I've got hundreds of records of this in bikejournal.
In the 3 times I've done it in April it's been 11.1km.
Same route.
Same bike.
Same cycle computer (and I've just checked that it is correctly set to 210cm wheel circumference, and it only has one setting).
Same front wheel (pumped up as normal).
So either the computer is on the blink slightly (but the elapsed time was correct), someone has been stealing large stretches of road, or space-time has warped slightly in SW London.
?
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Or it's been cold lately so the road has contracted
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Maybe differences in air pressure in parts of the route meaning your tyre changes circumference. Maybe your battery is getting flat and affecting the operation of the computer, perhaps missing a click here and there. Don't sweat it, you know how far it is.
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Could it be that your sensor has moved slightly on the fork so that it is missing a few revolutions?
I have the opposite problem, a route I ride regularly can vary between 10 and 11.5 miles. I realised what was happening when one day I rode past one point and my computer said I was doing 60+ mph!!!!
Damn Nokia (for it is their offices I am riding past when I get this issue!)
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I think it is Putney it self , I can feel it every time I go over Putney bridge :)
Or you just filtering more on some days than others. Cutting corners, lifting your front wheel and let it spin, zigzagging in traffic etc.
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Or the big wheelie you pull down the King's Road
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You've lost weight, compressing your tyre less and so getting a larger effective circumference...
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Greenbank - you say same bike & wheel, but have you changed the tyres?
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You wobble less than you used to?
:)
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Same tyre, and I'd expect tyre wear to decrease the tyre circumference and therefore increase the distance. So it can't be that.
Same weight for the last 6 months.
Last night's 5 pints and a curry had me wobbling more but, again, that should have increased the distance, not decreased it!
I'm not worried about it, it's just odd.
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Clip-on computer like a Cateye Astrale 8? You might have a bad connection.
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11.1 +/- 0.2 and 11.6 +/- 0.2 aren't very different. If the true value was 11.35 then they agree ;)
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I recall the first time we went out on our Thorn tandem, for a brief period the computer was registering speed but not distance. For no obvious reason it resumed normal functionality within a few hundred yards.
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The first cycle computer I had got confused when I went under some power lines ... does yours do the same? :-\ :)
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My Heart-Rate Monitor goes wappy when I call in to the Oakham Tescos. They have a radio curtain to stop trolley theft, which activates brakes on the trolley wheels.
Either that, or it's an OAP-homing-beacon, so that the Rutland Coffin DodgersSenior Citizens can find their way there.
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my commute has also shrunk, from 14.8km to 14.4km. I have noticed that traffic has been lighter recently, so I put it down to less weaving in traffic.
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Could the computer have reset the wheel diameter to its default?
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Could the computer have reset the wheel diameter to its default?
That'd make a huge difference. Much more than 4.5 %
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Clip-on computer like a Cateye Astrale 8? You might have a bad connection.
Velo 8, possible but the elpased time was correct (compared to my HRM watch), however it does keep the stopwatch going a few seconds after stopping.
11.1 +/- 0.2 and 11.6 +/- 0.2 aren't very different. If the true value was 11.35 then they agree ;)
I have over 200 entries in bikejournal of it being 11.6km +/- 0.05km. Never below 11.55km.
The first cycle computer I had got confused when I went under some power lines ... does yours do the same? :-\ :)
No power lines, however I do go under several sets of powered railway tracks (just south of Victoria). But the route is the same one I've done 200 times. If this was a factor then I would have expected to have seen it at least once before.
my commute has also shrunk, from 14.8km to 14.4km. I have noticed that traffic has been lighter recently, so I put it down to less weaving in traffic.
I don't have to weave much at all as I commute along relatively (for London anyway) fast roads, and last weeks commutes were no different to normal, certainly not 400m worth.
Could the computer have reset the wheel diameter to its default?
No, I checked it before making the original post. It's set to the right value for my tyre size. I then checked it again after another "short" commute.
It's back to 11.61km today, still on the same wheel size setting of 210cm.
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It's just a glitch in the Matrix. It happens when they change things ......