Here’s a quick reference sheet of common wheel sizes to use in the mobile app when pairing a Bluetooth speed sensor.

Size ISO Circumference (mm)
700×23 23-622 2097
700×25 25-622 2105
700×28 28-622 2136
700×32 32-622 2155
700×35 35-622 2168
700×38 38-622 2180
700×44 44-622 2224
700×50 50-622 2293
700×56 56-622 2325
27×1 3/8 35-630 2169
27×1 1/4 32-630 2161
27×1 1/8 28-630 2155
27×1 25-630 2145
26×1.25 32-559 1953
26×1.5 38-559 1985
26×1.9 47-559 2055
26×2.125 54-559 2070
29×2.1 54-622 2288
29×2.2 56-622 2298
29×2.3 60-622 2326
650b x 38 38-584 1995
650b x 42 42-584 2100

The ISO for most tires is found on the sidewall along with the diameter and tire width. This number can make it easier to find your size on the chart.

Please note this table is only a guideline and by no means complete or 100% accurate as wheel circumference can vary due to tire pressure, tread selection, tire thickness, rider weight, rim width, and load.

For more info on wheel circumference: we recommend checking out Sheldon Brown’s Calibration page.

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