Wheel Size Calculation; Determining Your Proper Wheel Size - Vetta c-500 Owner's Manual

DETERMINING YOUR PROPER WHEEL SIZE

Vetta cycle computers are programmed using the circumference of the wheel measured in millimeters. Note
that while your computer can be programmed to +/- 1mm for total accuracy, discrepancies of as much as
50mm or more will not have a significant effect on the accuracy of the unit for most normal rides.
The following chart lists the programming sizes for some of the most popular wheel sizes currently in use.
These numbers are estimations and may vary slightly from the size of your actual wheel depending on the
manufacturer of the tire that you are using.
TIRE SIZE
26 x 1.7
26 x 1.9
26 x 2.0
26 x 2.1
27 x 1.0

WHEEL SIZE CALCULATION

If the wheel size of your bike is not listed in the chart, follow these simple steps to calculate the calibration
number for your bike.
STEP 1
Measure the distance from the center of the front axle to the ground in millimeters. If you are measuring in
inches, multiply the number of inches by 25.4 to get millimeters. If you want total accuracy make this
measurement while you are sitting on the bike.
STEP 2
Multiply the above number by 6.2832 (2π).
STEP 3
Enter the resulting number into the computer.
PRESET VALUE
The C-500 has a factory preset wheel size value of 2074 (700 x 20c).
CIRC. TIRE SIZE
2035 27 x 1-1/4
2055 650 x 20c
2075 650 x 23c
2095 700 x 20c
2140 700 x 23c
CIRC. TIRE SIZE
2180 700 x 25c
1945 700 x 28c
1990 700 x 32c
2074 700 x 38c
2114 700c Tubular
CIRC.
2124
2140
2155
2170
2130