K2 Consistently High Mileage?

[dthempel]

Anyone doing group rides again and noticing "high" numbers for mileage? Rode with one others for the first time in almost a year this past two weekends and was seeing slightly higher numbers. Over nealy 50 miles, I was almost 2 miles over. I thought it was my partner's Wahoo as he had just complained about issues in a recent time trial and his unit pausing unexpectedly. After suggesting he hit the "fix my distance" button in Strava and nothing happened, I hit it on my ride, and suddenly "lost" 2+ miles and almost a full MPH over the course of the ride. Did it again on another ride and lost .7MPH (didn't notice the distance loss).

I think my K2 is using the GPS (not the wheel sensor), but now I'm not sure. If I don't "correct" the distance, am I also fudging numbers on any Strava segments or PRs that I'm setting. Wasn't feeling particularly fast on the bike this spring but some of the numbers were saying otherwise. Now I'm afraid to "correct" any more distances for fear of bumming myself out.

[Brian]

I ride with my Garmin Fenix 6 on my wrist. The Garmin and Karoo are always within a few hundred meters of each other. Neither is consistently higher than the other.

[roteta]

Had the same issue myself. The problem seems to be that the speed sensor sets in auto-calculation mode by default, and the karoo does a pretty bad job at auto calculating the wheel diameter, or at least mine did. Good news are it can be easily solved by just entering the right diameter. After some measurements, I have mine set now to 2107 mm with 700x25 tires and 68 kg of weight, with close enough results compared to strava, when auto-calculation got it to 2200+ mm.

[dthempel]

Thanks. It does look like it was the speed sensor or at least the K2's implementation of auto-wheel-circumference. This seems like an "easy" thing to figure out for a modern head unit. Use GPS distance briefly (a few thousand feet? less?) to calibrate. I've simply turned it off and removed the wheel sensor. One less thing to worry about the battery on... Seems silly to have one and not use, but if it's going to be 5% higher, that's dumb, too.

[OHarris]

I had the same problem. I did a group ride a few weeks ago. I had 31.88 miles while the rest of the group had about 28.8. That left me with a 1 MPH faster speed than the rest of the group which was impossible. I removed the speed sensor for the next ride and had, on a rain shortened route, 26.08 to the other's 25.67. I still had the most miles and the highest speed, but not embarrassingly so.

[Lightingguy]

My recorded distances are close enough to fellow riders using Garmins with no speed sensors (.2-.5 miles over 25 or so). As well, the distances when using Garmin speed sensors is pretty much dead on with what RWGPS says the distance should be,

[OHarris]

I put the speed sensor back on and will try to reprogram the circumference of the wheel. I don't know if I have had the problem before, but today, I had set a goal of finishing my route at 17.0 MPH. I was averaging 17.3 until I went under several large trees. I noticed the speed said 0 and my average dropped to 16.8 even though I was going downhill fairly fast.

[davidreyan15]

Had the same issue myself.

The problem seems to be that the speed sensor sets in auto-calculation mode by default,

and the karoo does a pretty bad job at auto calculating the wheel diameter,

or at least mine did.

Good news are it can be easily solved by just entering the right diameter.

After some measurements,

I have mine set now to 2107 mm with 700x25 tires and 68 kg of weight,

with close enough results compared to strava,

when auto-calculation got it to 2200+ mm.