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Author: Subject: Bike computer on buggy, different max speed, equal distance
hywelmartin
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[*] posted on 30-8-2014 at 10:56 AM
Bike computer on buggy, different max speed, equal distance


Hi all

I mounted a bicycle computer on my buggy.

After my first session I realized that the one I bought was to cheep.... salt water shorted the connections in the mount...
Returned it and got a better one. It works flawless, or...

It calculates the distance "right", at least it gets it near my phones GPS and My tracks.

But the speed differ, the GPS has a top speed of 46,84 km/h but my bike computer shows 50,1 km/h??

Is this because that the GPS needs a longer distance than the bike computer?







Flexifoil Sting 3.3
PL Reactor 2013 4.4
Home made Buggy (316L) http://eth0.se/gHTP
PB at least 51,09 km/h (31,7 mph)
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RedSky
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[*] posted on 30-8-2014 at 01:41 PM


Your PB made me laugh :D

I'd probably say that your bike computer is more accurate than your phone. Get yourself a dedicated GPS unit such as the Garmin etrex 10 then you'll know for sure.


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hywelmartin
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[*] posted on 30-8-2014 at 02:06 PM


I hope you laugh with me (not at me)....

My expense account is empty for now, I might have to borrow a proper GPS to double check my bike computer..

After you comment I might use the reading from my bike computer 58,1 km/h



Flexifoil Sting 3.3
PL Reactor 2013 4.4
Home made Buggy (316L) http://eth0.se/gHTP
PB at least 51,09 km/h (31,7 mph)
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soliver
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[*] posted on 30-8-2014 at 03:44 PM


I've heard a lot of people say that the phone GPS is not near as accurate as a dedicated GPS... Garmin etrex all te way!



I'm going to take a nap now
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RedSky
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[*] posted on 30-8-2014 at 04:02 PM


Quote: Originally posted by hywelmartin  
I hope you laugh with me (not at me)....


Nowt wrong with your PB. The wording made me laugh. :)
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hywelmartin
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[*] posted on 31-8-2014 at 12:56 AM


In my buggy area there is cell phone coverage and my phone uses GPS + GloNASS(Russian gps, works in the northern hemisphere) so I think that my problem is update interval between the GPS + GloNASS chipset and the phone itself.... hack on...

I tested two phones (one older only GPS and my newer GPS + GloNASS) on a flat surface and a constant speed whit my buggy = same spedd on all three
when accelerate the bicycle computer seems to show the correct speed, not the phones..





Flexifoil Sting 3.3
PL Reactor 2013 4.4
Home made Buggy (316L) http://eth0.se/gHTP
PB at least 51,09 km/h (31,7 mph)
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RedSky
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[*] posted on 31-8-2014 at 07:14 PM


Not so surprising. The GPS units might take a little longer to update their results whereas the bike computer isn't relying on a satellite. My eTrex 10 also has the option for GloNASS which I use for more accuracy. A fractionally short delay would not worry me for top speed results as I'm sure the data will come in.
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hywelmartin
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[*] posted on 5-9-2014 at 01:57 AM


I have found out that the GPS in the phone has an update frequency of 1 hz, a dedicated GPS usually has 10 hz. my bike computers update frequency is not time based, it depends on distance( the circumference of the wheel), so if I travel at 30 km/h(~18.6 mph) I get about 6,5 hz..










Flexifoil Sting 3.3
PL Reactor 2013 4.4
Home made Buggy (316L) http://eth0.se/gHTP
PB at least 51,09 km/h (31,7 mph)
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