AiM MyChron3 XG Log - Manual (Page 33)

Wheel
circumference
This function sets the wheel circumference (in mm or in
inches).
This parameter is fundamental to correlate the wheel’s
angular speed and the vehicle speed.
To run this function press button MENU/<< until you see
WHEEL CIRCUMFEREN
Then push MEM/OK to enter EDIT MODE: use button
MENU/<< to change numbers and button >> to change digit.
The blinking digit identifies the digit that can be edited.
The wheel circumference value can be set in a range included
between a minimum value of 0 and a maximum one of
9999 mm (0 and 399.99 inches).
When the correct circumference value has been set, press
button MEM/OK to save changes or press button VIEW to quit
without saving.
Phonic
wheel’s teeth
number
This option allows the user to set the phonic wheel’s teeth
number in order to measure the wheel’s angular speed.
The speed sensor, passing by a gear tooth, generates an
electric pulse which gets acquired by the instrument: if the
phonic wheel is made up of just one tooth, the instrument will
measure one pulse per lap, while, if it is made up of more than
one tooth, the number of pulses per lap will be greater than
one.
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