James Myers


Dr. James Myers
Director, Center for Multidisciplinary Studies ( RIT )

Dantheman62 Posting.

This is a great idea and there's lots of info out there on it!

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The average rider will produce between 125 and 200 watts using the Pedal-a-Watt. While this may not seem like much power, many pieces of equipment draw very little power and can be powered for long spans of time with small amounts of power.
Lights, laptops, and radios all draw small amounts of current at 12 volts DC. In addition, LED lighting and high efficiency fluorescent lighting now allow 200 watts to go a long way. A typical 25 watt fluorescent light bulb, which replaces a 100 watt incandescent bulb, will last 8 hours on 200 watts worth of power. LEDs (light emitting diodes) are even more efficient and will last days on 200 watts worth of power.
Want to know if you can power an appliance? Look at the label on the rear (usually by the power cord) and find out the "rating" which is in watts. For example, the label may read 30 W under electrical rating and this is 30 watts. If you are unsure, please email us with questions.
Power Consumption of Typical Appliances:

Small TV 100 watts
Large TV 200 watts
Laptop PC 10 watts
Desktop PC 75 watts
Stereo 20 watts
Charging a cellphone 5 watts
Hi Effic Desk lamp 15 watts

Any bicycle that is in good shape will suffice for mating to the Pedal-a-Watt platform. However, bicycles with wheels of larger diameters, such as 27 inches as opposed to 16 inches, create more mechanical advantage. Both street bikes, with very narrow, smooth tires, and mountain bikes, with wide, knobby tires, have been used with equal success.

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Watts is an instantaneous measure of power at any moment in time. Watt-hours is a measure of power over time.

For example, the Pedal-A-Watt, creates 200 watts of power. If you pedal for 2 hours, then you have created 400 watt-hours ( 200 watts x 2 hours) of power.

This 400 watt-hours would power a 100 watt light bulb for 4 hours, a 200 watt large screen TV for 2 hours and so on.
This is just amazing.


Bicycle Power Calculator

Assumptions:
Constant speed analysis
Drag coefficients reference "Science of Cycling", E.R. Burke, Leisure Press, 1986, pg 126.

Inputs
Wheel Diameter (inches) Crank Length (inches)
Desired Constant Speed (mph) Rider's Weight (lbs) Bicycle Weight (lbs)
% Grade (+ for uphill,- for downhill) Mechanical Losses (3-5% is typical) %
Gear Ratio (#Teeth Rear/Front)
Air Resistance Coefficient (lbf*s^2/ft^2) = Cd*FrontalArea
Rolling Resistance Coefficient (lbf/lbf)

Calculated Outputs
Total required input power from the rider HP Watts
Power needed to overcome air resistance HP %
Power to overcome rolling resistance in tires HP %
Power needed for elevation change HP %
Power lost to mechanical losses, friction, etc. HP %
Calories burned per mile kcals (assuming 28% efficiency in conversion to human power output)
Average Pedal Force Lbs Average Traction Force Lbs
Pedal Speed RPM Tire Speed RPM

You are visitor # since 14 March 2005

copyright 1999 Penn State 19 August 2005 by John S. Lamancusa - Penn State University (jsl3@psu.edu)
Accuracy checked by ME288 Product Dissection class, Underlying Equations
Modified to work with Netscape 4.0 by Matt Lindenberg

Go to Product Dissection Homepage


Other Calculator sites

http://www.machinehead-software.co.uk/bike/power/bicycle_power_calculator.html

http://www.noping.net/english/

http://bicycle-power-calculator.10001downloads.com/download

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