K2 Wheel Circumference auto-calibration

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Maciej Kujawa

I have an impression that wheel circumference auto-calibration is a mess when having two or more speed sensors paired to Karoo 2. The value of 2105 mm was given to my 2nd speed sensor (lower on the list and not connected at the time) on my gravel bike when I was riding my race bike with 25mm wheels (should be around 2105mm). Apparently the value of 2200 mm was given to my 1st sensor of the race bike when riding gravel bike... HH should definitely look into this. Not to mention that the 2nd sensor is being switched between my MTB bike and gravel bike.

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    Jami

    Hello Maciej!

    There is actually a known issue with wheel circumference auto-calibration - our software team is working on a fix for that. I'm sorry for the inconvenience.

    The workaround is to set wheel circumference to manual and input the correct circumference. You can either utilize a chart to get the approximate circumference or measure it for greater accuracy. 

    Here is a website with a fairly comprehensive chart. Keep in mind that different brands/models of the same size may actually measure out to slightly different circumferences due to variations in tire design. 

    This site also has a chart, though less comprehensive. What it does have is some good instructions/methods for measuring the tire's circumference. This will always be the most accurate method.

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    Bruno

    In many comments from 2 years ago, the measure is overrated. Currently with my 28mm tires the k2 gives me 2106 mm, while I measured on the ground: 2127mm. There is still a beug, but now down. Hammerhead, you need to fix this or remove this feature because it is useless.

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    ZAX

    this issue is still there, I connect my e-bike to karoo2, auto circumference, and the speed source is enabled by default, I don't know what wheel data it gets, the result is that the riding distance it recorded is totally wrong, way longer than actually distance, and when I disable the speed source (because it said if this enable, karoo2 will using speed sensor to calculate distance and override the GPS, if it set to disable, then karoo2 will using the GPS distance), turns out the riding distance is way shorter than actually, what happened? because my e-bike is connected as one sensor (battery, power, speed, cadence), I can't disable the speed sensor alone, so what should I do? set the Wheel Circumference manually? no matter what speed source enable or disable? I've tried Garmin 1040 and Magene C406 and Garmin Enduro 2, connected all my e-bike sensor with no issue, only Karoo2 have this issue, please help

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    Paul de Jong

    My Lezyne speed sensor is also underestimated by the K2 auto-calibration feature. Using just gps seems to provide better distance but more erratic speeds (specially in covered areas such as woods). Still strange as GPS should calibrate the sensor, not worsen it…

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