Karoo 2 : Problem with calculated distance
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Last weekend I went on a 3-day bike trip and experienced some weird behavior on distance calculation.
Day 1 - shown distance correct, mid ride charging by powerbank with karoo cable did not work.
Day 2/3 - used a different cable at the start of the ride which did make the charging work, but the shown distance was wrong.
If I export the original fit-file of day two and do a conversion to gpx, the differences are : 312.80km for the fit-file and 359.96km for the gpx (which is the correct one). Quit a lot.
Software version : 1.200.1016.3
Garmin Speed Sensor : Manual set at the appropriate wheel size
Measurement settings Karoo : everything metric
I haven't reset my Karoo yet, so I can supply additional data if needed
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Official comment
Hi All,
This issue has been addressed in today's release. Thank you for bringing this to our notice!
Comment actions -
Sounds like your wheel sensor stopped sending the info to update the distance. Where as the co-ordinates will still get written into the fit file. Attach your Fit files to this page and lets take a look at the data with in the Fit file.
Personally I wouldn't use speed sensors more hassle than they are worth, I just use gps tracking, never had an issue in 15 years even in Forests, I can live with the occasional few hundreds yards through tunnels.
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Sounds like a plan :-) I'm using the speed sensor because the shown speed was kind off all over the place. It had a variation of roughly 3 kilometers per hour. That annoyed me. With a speed sensor it was definitely more stable.
The fit file of day 2 : https://we.tl/t-JjzoOZUnFM
btw the speed sensor was connected, I did check the setting during the ride.
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Pretty simple, entered the wheel size 700x25c on google and it came back with 2105mm. So that's what I went with.
I did the same when I had a 700x28c, and at the time that worked out just fine for several months. Last weekend at the first day of biking it was working accurate, day 2 and 3 it suddenly changed.
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If you use Conti's look here: https://www.continental-tires.com/bicycle/service/faq/tire-characteristics
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So I did a factory reset, reconnected all sensors and used the 2133 as circumference according to the table Jan Kuijsten posted. It did not make any difference.
I did a comparison with my Garmin Venu using GPS and de Karoo with my speed sensor. The results :
- Garmin : 56.0 km
- Karoo : 46.0 km
The problem must be somewhere in the speed sensor or the Karoo. Can't just figure out exactly where :-x
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I am having the same issue. My distance on Karoo is overstated sometimes by as much as 5 miles depending how far I ride. I compare the K2 distance with that of Strava which I use simultaneously to record a ride. I use the Garmin speed sensor. I don't know where on K2 to input the circumference of my wheels which was available on the earlier versions of the K1s. Any suggestions would be appreciated. Thanks.
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Hello John,
I have made some progress along the way. I changed the order of the sensors so the build-in GPS is on top. You can just slide them in the order you want. Changing the circumference can be done on the screen after tapping the Garmin speed sensor. Scroll down, select manual and enter the size you need.
For me this fixes the problem calculation the correct distance, just wondering if the Karoo is using the speed sensor with this configuration...............
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@Benno: this morning biking through the forest I already noticed the speed was varying from 28 to 32km/hour. When I was riding approximately at 30km/hour. That looks like the Karoo indeed is not using the sensor. Your suggestion that it might be weight and tire pressure, for a small difference that seems logical. But if you take a look at my post with the Garmin comparison data. That is a deviation of 21.7%, correct me if I am wrong but weight and tire can't make it be that much off
@Edgar: it was working for me as well, until it didn't. No reason (firmware update or something like that)
Thanks for the replies given :-)
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Small update. Last Friday I changed the battery of the sensor and did a full hardware reset of the Karoo. To my surprise it was working again! Yes.... it did work for two whole days. Yesterday same old story with somewhat of 20% deviation.
no settings changed, just fell back into old behavior
Highly annoying............
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Well there is for sure a Problem with Garmin speed Sensors. I'm facing that issue since the beginning no matter what software update I m on and with three Garmin speed Sensors on different bikes. My one is still at around 25kph - 2kph to "fast". I have the same Sensor connected to my garmin fenix and it shows the right speed at the same time - as I already mentioned it on some other posts if I only use GPS without the speed sensor on my Hammerhead speed is correct ...if the autocalibration would work correct it should fix that but doesn't so far :( ... and no I wont type in a wrong wheel circumference to compensate the issue as the circumference is shown correct in the karoo which is even more weird .... so maybe just a wrong calculation of speed or an issue with mph / kph ... dont know ... hope they really gonna fix that problem.
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A more accurate way to measure wheel circumference:
Measure when the wheel is at normal riding pressure and the bike has all the gear on it except the rider.
Use the normal circumference measuring technique of rolling the tire along a straight line and then measuring the line length. This is the unladen circumference unlCircumference.
Calculate the unlRadius from the unlCircumference using unlRadius = unlCircumference / (2 * 3.14159).
Measure from the ground (directly under the axel) to a point (that is easily repeated) near the axel. This is tempRadius1.
Repeat this measurement with the rider on the bike. This is tempRadius2.
Subtract tempRadius2 from tempRadius1. This is diffRadius.
Subtract diffRadius from unlRadius. This is the effective Radius effRadius.
Use the effective radius to calculate the effective circumference: effCircumference = 2 * 3.14159 *effRadius
Note: use the same wheel that the speed sensors is on. Units are millimeters.
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