Distance mismatch.

Debian

New Member
Location
West Midlands
My commute, as measured by my computer is a fraction over 7 miles each way.

I've recently started to use Google My Tracks and it measured my commute at nearly 5 1/2 miles.

Interestingly though, my computer and My Tracks agree on my average speed and journey time. One of them is wrong but which, and how?
 

gaz

Cycle Camera TV
Location
South Croydon
Well if the avg speed and journey time is the same... then the distance is the same. Simple Maths... D=ST
D being distance
S being average speed
T being time
 

Moodyman

Guru
Doesn't Google use GPS, whereas most computers use the wheel rotation?

I read somewhere that GPS can be slightly inaccurate (not as much yours though) as it doesn't take into account the cyclists riding pattern.
 
Moodyman said:
Doesn't Google use GPS, whereas most computers use the wheel rotation?

I read somewhere that GPS can be slightly inaccurate (not as much yours though) as it doesn't take into account the cyclists riding pattern.
Thats about right the gps draws up straight lines between points whereas the cyclist might have wobbled, etc but you're right that wouldn't cause such a large discrepency as posted.
 

Norm

Guest
Debs, you haven't changed tyres without changing the settings in the computer, have you? I might expect a difference of 1%-ish but 20% is too much to be just different cornering radii etc
 
OP
Debian

Debian

New Member
Location
West Midlands
Gaz - both give the same average speed and journey time, just different distances.

EDIT - yes, sorry, woken up now. I'll do the calc.
 
OP
Debian

Debian

New Member
Location
West Midlands
Norm said:
Debs, you haven't changed tyres without changing the settings in the computer, have you? I might expect a difference of 1%-ish but 20% is too much to be just different cornering radii etc
No Norm.

Computer was set up on current tyres and pressures by measuring distance travelled for five rotations.
 
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