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.
26 x 1.7
26 x 1.9
27 x 1.0
700c Tubular
26 x 2.1
700 x 38c
26 x 2.0
700 x 25c
700 x 28c
700 x 32c
27 x 1-1/4
650 x 20c
700 x 23c
700 x 20c
650 x 23c
2035
2055
2075
2095
2140
2180
1945
1990
2124
2140
2155
2074
2170
2114
2130
TIRE SIZE
TIRE SIZE
TIRE SIZE
CIRC.
CIRC.
CIRC.
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 (2
π
).
STEP 3
Enter the resulting number into the computer.
PRESET VALUE
The C-16 has a factory preset wheel size value of 2074 (700 x 20c).
