Performance Axiom Owner's Manual

Cyclocomputers
Owner' s Manual

Determining Wheel Circumference

In order for the Axiom Cyclocomputer to accurately compute distance and speed, you must enter your actu-
al wheel circumference. There are two methods of determining your wheel circumference: 1) the Tire Size
Chart Method or 2) the Roll Out Method (the Roll Out Method gives you a higher degree of accuracy).
Method 1 - Tire Size Chart Method
Using the chart below, locate the size of tire that you will be using on your front wheel. The wheel circum-
ference (in mm) is shown to the right of the tire size.
Example: for a tire size of 700x25, the corresponding wheel circumference is 2086 mm - 2086 is the number
you need to program into your computer.
Tire Size
20 x 1.75
24 x 1
24 x (Tubular)
26 x (Tubular)
26 x 1
26 x 1.25
26 x 1.5
26 x 1.9
26 x 2.2
26 x 1
Method 2 - Roll Out Method
Stand your bicycle upright. With your tire inflated to its proper pressure, rotate your wheel so that the valve
is located at the bottom. Make a mark of the valve's location on the floor. Roll the bicycle one complete
wheel revolution, in a straight line, until the valve is again at the bottom. Mark this new location of the
valve on the corresponding point on the floor. Measure the distance between the marks, in millimeters (mm).
This is the value of the wheel circumference that you need to program in to your computer. (Note: inches multi-
plied by 25.4 converts inches into mm; i.e. 1 inch = 25.4 mm).
Wheel Circumference (mm)
1528
1753
1759
1929
1913
1967
1974
2048
2074
3
2068
⁄
8
Valve
Tire Size Wheel Circumference (mm)
5
27 x ⁄
8
27 x 1
1
27 x 1 ⁄
8
1
27 x 1 ⁄
4
700C (Tubular)
700 x 20
700 x 25
700 x 28
700 x 32
700 x 35
Distance (in mm)
2077
2105
2123
2142
2083
2058
2086
2096
2114
2139
Valve