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Old 10-17-2020, 05:42 PM   #51 (permalink)
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So i overcame the math anxiety and used the power equation from "The Leading Edge" by Goro Tamai To calculate power requirements. Given a gross weight of 300 lbs or 1335 N and 0.40 square meter frontal area, at 30 mph and the Cd of 0.3 the power needed is about 360 watts. This is about 1/3 less than an bare bike and an adult rider with a Cd of 0.60.

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Old 10-18-2020, 03:39 PM   #52 (permalink)
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Subscribed. If you include my daily paper route that I did by bicycle, I have about 5 decades of bicycle commuting experience. As the OP has stated “If it were easy, everyone would be doing it.” There are a number of design considerations that make reducing aero drag on a bicycle very difficult. Aero drag on a Battle Mountain streamliner can be very low but they are totally impractical to ride. A faired recumbent trike can strike a good balance between function and low drag but you add weight, length and perhaps some issues with visibility. Adding a fairing to an upright cycle can add frontal area in crosswinds. I did the bulk of my commuting with a drop bar bike which allowed several hand positions including getting flat and low when confronted with strong winds.

I look forward to your progress with this.
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Originally Posted by freebeard View Post
The power needed to push an object through a fluid increases as the cube of the velocity. Mechanical friction increases as the square, so increasing speed requires progressively more power.
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Old 10-19-2020, 01:51 PM   #53 (permalink)
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It surprised me to see that rolling resistance was as much as a factor with common mountain bike tires. I calculated 175 watts for tires, tubes, and max weight. Air pressure of 65 psi is often recommended for these tires. Next tests will be for a reinforced front piece.
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Old 11-27-2020, 02:04 PM   #54 (permalink)
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Using 1/2 in plastic pipe 45 elbows, PEX tubing, and steel tent pole tubing I was able to make a sturdy hoop for a front fairing. First try was just too tall to see over properly. The issue of seeing the road and the speedometer requires further work. In the mean time I have been cutting strips of .012 inch by 6.5 inch plastic to make spoke covers for the front wheel. Reducing rolling drag by half seems possible. See Stan's No Tubes at www.notubes.com. The site bicyclerollingresistance.com gives specifications on tires.

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