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April 2005

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Subject:
From:
Indrek Rebane <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Indrek Rebane <[log in to unmask]>
Date:
Tue, 26 Apr 2005 21:59:48 +0300
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Hi Bill,

Bill Kasprzak wrote:
> Ya know, it never ceases to amaze  me where some of the information
> passed along on this site comes from.

> Where does all of this "stuff" come from?

Like we say around here: "Women in sauna told".

In reality, transmission efficiency over chain-gear system is below 99%.
see:
http://www.jhu.edu/~gazette/1999/aug3099/30pedal.html

Bit more about transportation efficiency:
http://www.pnas.org/cgi/reprint/95/10/5448.pdf

also
"For instance, the bicycle is the most efficient machine ever created:
Converting calories into gas, a bicycle gets the equivalent of three
thousand miles per gallon. A person pedalling a bike uses energy more
efficiently than a gazelle or an eagle. And a triangle-framed bicycles
can easily carry ten times its own weight - a capacity no automobile,
airplane or bridge can match."
Bill Strickland

Google for more.

> P.S I'd like to know what the efficiency is for a person on roller
> blades. I suppose the friction coefficients relating to the road
> surface and the quality of skate bearings play a role but I'd sure
> like a rough idea.

On link above, they say biking is more efficient than ice-skating. I
can confirm from my own experience that cycling is less tiresome at same
speed than roller-blading.

Indrek

--
  Indrek Rebane           |      Borthwick-Pignon
  Electronics Engineer    |    Tartu Science Park
  Phone: (+372) 7 302 641 | Riia 185, 51014 Tartu
  Fax:   (+372) 7 383 041 |               Estonia
  [log in to unmask]        |         www.bps.co.ee

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