Speed Sensor Calibration for MTB / Strava Distance Incorrect?

Common sense would tell me that a speed sensor is a good idea for MTB - as you’re often going slowly, going around tight corners or going up steep things.

But it’s seeming to me that it’s impossible to get a calibration that matches up consistently with what Strava says is the distance. I’m wondering if this is just a Wahoo thing or if it’s a Strava thing. Has anyone else felt the need to ditch the speed sensor?

The back story on this: A year or so ago I did a 50km MTB race and the distance ended up being way off at ~60km. Originally I believe this was based on 29" x 2.3 setting on the Wahoo of 2.326 which I guess is not right when you run low pressure / narrow rims. For a weekend ride it doesn’t matter too much, but if you’re doing any kind of event you need the reported distance to be fairly close to being correct.

Getting scientific - I’ve compared Segment length and Strava distance to the recorded distance. Then worked out the correct wheel size based on the distance Strava says and I get some pretty varied results.
Calibration value / tyre roll-out:
Road Segments / Gravel Grind / Commute - 2.25
Trails - 2-2.1 but then if you compare individual segments the calibration can vary from under 2 to 2.2
With that kind of variance we’re talking being 1-2km difference over a 20km ride - which is just bonkers surely?

If Strava’s corrected distance is based on GPS or segments, then presumably it’s likely to suffer from cut corners/inaccurate tracks pretty massively for MTB segments.

The distances for longer races are often off. 60km for a 50km seems extreme though.
I’ve used several different Garmin devices on a similar distance over the last few years. The distance is always within a km.

Is there an auto calibration setting on the Wahoo? My garmin units allow for the speed sensor to auto calibrate and I find it pretty accurate on trails.

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Yeah maybe worth another go.
It’s a long while ago - but I think I got annoyed with Auto always reading a bit high. It’ll be worth a test though.

Surprises me if there’s no-one else out there with this issue.

FWIW, mine seems to read quite close(Wahoo hub speed sensor). On a 29” MTB.

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