Tire Diameter - Android App

Having issues with the speed I am seeing in the App. Hugely variable and unstable values that can jump from 20 to 200km/hr…
Believe this relates back to the “Tire Diameter” setting in the “Settings / Bike” section of the android app.
In case it makes any difference I am using a Wahoo Core combined with the Android App.
Is this the 32 of the Tire Diameter (32-622), or the Wheel & Tire Diameter (70.5cm), or something else?
In what units should the measurement be entered? (cm, mm, inches,…)
Appreciate any clarity that can be provided on this.

Some trainers appear to have different data for this, notably the Elite Direto. Not sure about the Wahoo Core. 662 is the default wheel diameter which includes the tire size.

Thanks, will try that tomorrow, and see what I get.


I now have a Elite Direto XR; during today’s workout, the speed in Xert reached 220+ km/h, so I had to change the setting to “Speed From Power” instead. What value should I set for the Tire Diameter parameter in the options ?

According to Elite’s support:

The circumference configuration on the external devices must be:

Real circumference / ( subdivided per ) 12.1.


  • Wheel circumference = 2095 mm, so 2095 / 12.1 = 173,14

  • Must be set as 173 mm on the device

Is it correct to use that calculation in Xert ?

It is almost universally better to use Speed from Power rather than from the trainer, even with a proper diameter setting. Using Speed from Power, it doesn’t use the diameter. The Direto does require very different settings if you plan to use speed from the trainer. That sounds correct.

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