Sigma BC 1009 STS Manual Del Usario página 28

6.4 Wheel size chart (Radgröße / Wheel size / Circonference de roue)
A
B
28
mm x 3,14
1x
km/h:
WS = mm x 3,14
mph:
WS = mm x 3,14
km/h:
WS = mm
mph:
WS = mm
= WS (mm)