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Old 04-10-2008, 08:26 AM   #18 (permalink)
newtonsfirstlaw
EcoModding Apprentice
 
Join Date: Dec 2007
Location: Melbourne
Posts: 152

The Mighty Mira - '92 Daihatsu Mira
90 day: 61.32 mpg (US)
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Quote:
Originally Posted by LostCause View Post
The number one reason not to ride is safety. I've heard that you are ten times more likely to die riding a bicycle then driving a car (no idea if that is adjusted in any way, though). The famous adventurer Steve Fossett said the only time he was truly scared was when biking the streets of Chicago.
If only an extensive network of class I bike paths existed like the freeway infrastructure...It took me 40 miles of circuitous bike/street paths to get to a destination 20 miles by freeway. I think it's some kind of conspiracy...

- LostCause
God yes. Correct on both counts.

Some people probably wonder where I went in the last few months. I spent a good deal of it thinking about velomobiles and infrastructure.

What is really key is the infrastructure. Get cars down to human powered speeds with speed limits and traffic calming (i.e. 30kph or so), and they aren't very dangerous. You'd have to be very unlucky to have a collision or die in an accident. This is appropriate on all residential street areas.

I think it's also key to have bicycle bridges over the major roads, so that a person can get from any 30kph section of road to another safely. I think those two things alone will make bicycles popular because it enables a safe option.

However, what human powered transport really screams out for is an elevated grid of freeways with interchanges (which can be made much cheaper than roads because the load needed to carry is much less). As you who ride bicycles know, the human engine is very, very anemic compared to any sort of engine. With aerodynamics, the power loss can be made very small, and average sustainable speed quite large - i.e. 40-50kph with something like the WAW or the Quest. The key is to eliminate all stopping. The solution to that is the interchange and grid freeway system.

A thought experiment:
Q: A velombile is traveling at 45kph. What is the Kinetic Energy possessed if the rider + velo is 120kg?

A: E = .5 * mv^2
= .5 * 120 * 12.5^2
= 9375 Joules

Q: How far can that velomobile travel with the energy lost in that stop if 100 Watts is expended to maintain that speed of 45kph?

A: t = W/P = 9375/100 = 93.75 seconds

At 12.5m/s, you will travel 1171m in 93.75 seconds.

So, every time you get up to speed and stop, you have wasted the equivalent in effort that would have allowed you to travel 1km. Let that sink in.

Think how many forced stops are involved in a typical trip, and wonder why velomobiles aren't yet as practical as they are on paper. It's because they need the infrastructure! But build the infrastructure, provide appropriate legislation, and boom.

For bonus points, convert the kinetic energy to gravitational potential energy and compare to a cyclist traveling at typical cycling speed, and the height of a rise (or road bridge) that can be attacked without having to pedal. The difference is large, all because there is 4 times as much energy involved in traveling at twice the speed.

So that's why I'm not working so hard on ecomodding anymore. My next step is to get a house with a viable path to work via bike-friendly infrastructure. Cars just don't do it for me any more, but my love of aero remains.
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"Every body perseveres in its state of being at rest or of moving uniformly straight forward, except insofar as it is compelled to change its state by force impressed." - Isaac Newton
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