[CR]New Sheldon Brown article--Slide Rules & Gearing

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Date: Sat, 24 Aug 2002 16:17:58 -0400
To: internet-bob@bikelist.org, Classicrendezvous <classicrendezvous@bikelist.org>, fixed-gear@lists.davin.ottawa.on.ca
From: "Sheldon Brown" <CaptBike@sheldonbrown.com>
Subject: [CR]New Sheldon Brown article--Slide Rules & Gearing

Sometimes a 400 year old instrument is faster than your computer!

The slide rule was invented back in 1625 by William Oughtred, based on John Napier's 1614 discovery of logarithms. This was the indespensable tool of mathematicians, scientists, engineers and mathematically literate lay people up until the early 1970s when solid state electronic calculators became available.

Computers are wonderful things, and among their many uses is the rapid calculation of bicycle gearing. I have written (with some volunteer programming help) a Web based system for calculating the gears of multiple speed bicycles. http://sheldonbrown.com/gears

This and similar systems are excellent for generating charts of multiple gear systems. They are less than ideal for the fixed-gear or singlespeed rider, however. For calculation of single gears, I usually fall back on much older technology, my trusty slide rule!

The slide rule generally only offers 2-3 digits of precision, but for bicycle gearing that's quite sufficient, and the extra digits provided by many computer applications only obscure things.

My latest Web article shows how to do this. I'm very proud of the JavaScript slide rule.

See: http://sheldonbrown.com/sliderule.html

Sheldon "Slipstick" Brown Newtonville, Massachusetts +---------------------------------------------------------------+ | Anyone who can't use a slide rule is a cultural illiterate, | | and should not be allowed to vote. --Robert A. Heinlein | +---------------------------------------------------------------+
      Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772, 617-244-1040, FAX 617-244-1041
            http://harriscyclery.com
       Hard-to-find parts shipped Worldwide
            http://captainbike.com
    Useful articles about bicycles and cycling
            http://sheldonbrown.com