iBike Newton+ Operating Instructions Manual page 32

7. Hold the bike still and upright, with the front wheel pointed straight ahead. Click
the center button. The horizontal bar counts down to zero. Do not move the bike.
8. Once the bar disappears, the words "turn 180" flashes again. Turn the bike 180
degrees; the bike now points in the original direction with the tires resting on the
same two spots.
9. Hold the bike still and upright, with the front wheel pointed straight ahead. Click
the center button. The horizontal bar counts down to zero. Do not move the bike.
10. Once the bar disappears, if the calibration is good the words "GOOD TILT" flash a
few times and the iBike advances to the CAL WIND screen.
11. If you moved the bike during any of the three "countdowns" you may get the
message "BAD TILT". If so, repeat steps 2-10, making sure you point the bike
straight ahead and hold it as still as possible during the calibrations.
The "Tilt Calibration" process is performed only one time; you do not need to repeat it.
"EST FRIC" (estimate Frictional drag)
•
Bikes have an intrinsic level of rolling resistance (frictional drag) that is dependent on tire
type, tire pressure, and road surface. This factor is called "Crr" (coefficient of rolling
resistance) and Crr is a number generally between 0.003 and 0.008. The higher the Crr
the higher the rolling resistance.
For example, with normal bike tires a very smooth velodrome track will have a Crr of about
0.003; asphalt will have a Crr around 0.0055, and dirt roads have a Crr of 0.008 or higher.
The Newton+'s coast down process can measure Crr (in addition to CdA, the aerodynamic
resistance) but in many cases it's easier and faster just to assume a value for Crr.
Assuming a value of Crr can improve the accuracy of the CdA measurement.
The default setting for EST FRIC is YES; that is, in the EST FRIC YES setting the Newton+
will assume a fixed, user-set value of Crr, even when coast downs are performed.
The default value of Crr has been set at the factory to 0.0055; on the Newton+, this reads
as "55" in the screen. The value of Crr can be set by the user.
To use the estimated Crr feature do the following:
1) Go to Setup/RACR YES/EST FRIC.
2) Click the center button; the bottom screen flashes. Use the up arrow to select YES,
then click the center button to accept. "done" flashes
3) The screen FRIC appears; the number at the bottom is the value of Crr currently
stored in the Newton+.
4) To change the value of Crr (fric) click the center button. Adjust the digits to the
value you want. Fric = 30 corresponds to a very smooth velodrome; 55 is an
average asphalt road; 80 is rough concrete; 100 or higher is dirt roads. These
values are approximate; you can get more exact values from the web.
5) When you've entered the value you want, click the center button to accept. Done
flashes and the Newton+ proceeds to the next RACR screen, TSS
REMEMBER: IF YOU SET EST FRIC TO "YES" THE VALUE SHOWN WILL BE USED BOTH IN
ESTIMATED DRAG COEFFICIENTS AND AS THE ASSUMED VALUE IN COAST DOWNS.
If you do NOT want to use the estimated Crr feature do the following:
1) Go to Setup/RACR YES/EST FRIC.
2) Click the center button; the bottom screen flashes. Use the up arrow to select NO,
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