


Wind on Rider
Data Input Instructions 
U
se the Menu Input Form or the Advanced Input Form. The Menu Input Form lets you pick a course and wheels from a lists. However, it does not let you modify the course or the wheel parameters. If you want full control over the data, use the Advanced Input Form.
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Course
Courses may be out and back or point to point. Select closed course or point to point. For a closed course, enter how many laps. Data for a closed course is tested to insure that the course does close in direction, distance, and elevation. Don't enter commas in numbers. You may enter decimal points. You must complete all data elements of a row. You may leave rows blank. You may skip rows. Example data has been entered into the form. Overwrite this data with your own.
Wind Speed
Wind speed is in m/s. Direction is in degrees from north as measured by a compass. The number entered for Wind Variability is used to create a wind speed in a range plus or minus this amount. The model selects a uniformly distributed value from this range for the value of wind speed. If you use wind variability, please be aware that you answered will change with each evaluation even though you don't change the data. This is because wind speed used in the model is a true random variable. The table allows for wind to change direction on different parts of the course. This could happen as a road turns into a valley or up a mountain gorge. Note that the wind direction is not relative to the direction of the rider's path; it is the direction from which the wind is blowing.
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You may enter data in the FreeForm Area instead of field by field. You can do this easily by copying and pasting from another application where you keep your data. Do observe the form shown with the list elements separated as with {{}, {}, . . .}. Data elements and order are the same as above.
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Estimated minimum speed is used to estimate the time it takes to complete the course (used to compute how long the model should run). If this speed is too slow, the model will run for a long time. If it's too fast, the model will not run to completion. A typical error message will say something about "Interpolation functions being out of range . . ."
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Wheel Parameters
Get weights by weighting each wheel. Get rotational inertia by measuring the wheels. The rear shelter is the amount by which the drag on te rear wheel is reduced due to shelter from the rider's legs and seat tube.
Use the menus (menu input form) to select wheels for evaluation.
Or use the advanced input form: Enter coefficient of drag for drag values. Or use drag in pounds force (lbf) or grams force (gmf) in which case you must supply a speed and an air density. The speed and air density are used to convert the drag force values to equivalent drag coefficients. If the air density for the drag is not known, there is a good chance that the default value would be appropriate. The yaw angle values must range from 0 to 90 and be strictly increasing.
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Equivalent Drag
Often one wants to know the effect of a reduction in drag for the rider and bike. Use this input control to reduce drag by an amount that is equivalent to the parameters given. For example, if a manufacturer quotes a 0.1 lbf reduction in drag at 30 mph under standard air density, these data can be entered here and the model will reduce the drag on the rider and bike by an amount that is equivalent for the speed and air density being used in the analysis. A choice of input units is given. The results are applied to the test rider only. Values should be small in relation to total drag on rider and bike.
See the Glossary for additional definitions and explanations.
© 2000 Tom Compton

