3. Roll the wheel one complete revo-
lution until the valve stem is again
at the 6:00 position. Read the
tape directly under the valve and
note the distance in millimeters.
(To convert inches to millimeters,
multiply inches by 25.4). Use this
number to replace the default
(default values are 2073 for
wheel one, and 2134 for wheel
two) when programming your
computer. (See figure 12).
You may also use the following quick-
reference chart:
Generic Tire Size Chart
This chart is for non-Specialized tires
26 X 1.75 2140
26 X 2.0 2074
26 X 2.1 2090
650C X 20 1945
700C X 26 2124
700C X 38 2170
Programming the circumference
To enter the tire circumference num-
ber, select the Speed (SPEED) mode
and hold down the "SET" button for
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currently selected tire size for wheel
option #1. To scroll through the pre-
programmed tire sizes tap both the
"MODE" and "SET" buttons simulta-
neously. When you reach the desired
tire size press the "SET" button once
to select it and enter Easy Calibration
Mode for wheel option #2. Follow the
same procedure to program the wheel
#2 tire size and tap the "SET" button
to exit Easy Calibration Mode.
Roll Out Method
The roll out method will provide the
most accurate computer calibration
and can take into account variables
such as inflation pressure, rim width
and rider weight.
1. Extend a tape measure out to
3000mm (120 inches) and lock it
in place.
2. With your tire inflated to its prop-
er pressure, place the valve at the
6:00 position (at the bottom)
directly over the start of the meas-
uring tape.
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