The Mechanical Evolution and

Social Development of Bicycles

        The piano had to wait for silicon steel with so little stretch that it stays in tune for a reasonable length of time at the tension required in a piano string.  The chain drive bicycle had to wait for a method of hardening steel, cheap enough for mass production.  Otherwise the sprocket teeth and rollers in the chain would wear out in a few miles.  Before that bicycle pedals were connected directly to the wheel without even a free wheel.  Naturally the front wheels on some high wheel bicycles got as large as the longest legged people could reach the pedals to make a faster bicycle.  The absence of a free wheel made the high wheeler a “unicycle with a training wheel” and comparably dangerous.  Some athletic riders coasted with their feet on the handlebars with the pedals spinning uncontrollably fast below.  Now we know why the first chain drive bicycles were called safety bicycles.  So the chain drive bicycle was responsible for a great deal of the gaiety of the Gay Nineties.  Imagine a salesman explaining to a potential buyer of one of the new “safety” bicycles that its pedaling characteristics were that of a 60 inch high-wheeler.  It didn’t “just happen” that to this day the various gear ratios of derailleur bicycles are measured in “gear inches”, the diameter in inches of a high wheeler with comparable speed potential from pedal power.

        We will skip over the details of coaster brakes and 3 speed rear hubs to the 10 speed “racer” because that is when snob appeal entered the social development of bicycles in a new way.  Ten speeds sounds more than 3 times as good as 3 speeds.  The reality is that all 10 speeds are not uniquely useful, and now we have 18, 21, and 27 speed derailleur set ups, in which many of the ratios of  the small whole numbers of teeth engaging each other are identical (24/12=48/24).  All the extra sprockets are there to permit the chain to pass from one to the next promptly and smoothly(?), so there many more than enough intermediate steps.  This means that when you are shopping for a new model, all you really need to look at is the difference between the lowest and highest ratios to cover a sufficient range.  For a road bike a 4/1 ratio of gear inches is enough regardless of the number of intermediate steps.  Why worry?  As the individual gear wheels get thinner and the matching chains also get thinner the whole set up gets more fragile.  The components not only wear out faster but become touchy to keep tuned-up.  Unnecessary fragility is related to the fetish of lightness and racing.

       Who needs a racing bicycle in the first place: professional bike racers.  You seldom see an amateur cyclist on his racing bicycle with his hands down on the grips provided.  So racing handlebars have long been oversold.  Lightness is utilitarian up to a point, but the extremes are not only costly but also inconvenient.  Consider aluminum alloy chain wheels, a tiny weight saving and a high price in inconvenience because you can wear them out in a year of hard riding.  The lightest available tires are even more of a hassle.  For everyday commuting around home I recommend a 5 speed model with an  Ashtabula crank (indestructible, because it is forged in one piece all the way from peddle to peddle) and a basket (perish the thought).  The 5 speed feature is doubly beneficial: how else can you avoid the need for a pants clip?  Besides, a chain guard is much better for keeping grease off your dress clothes even if you don’t wear pants. Maintain your bike well, but if it looks a little shabby, so much the better---it is less likely to be stolen if you fail to lock it when you stop at the delicatessen.

       Summary: make your bicycling convenient so you do it often enough to maximize your health.

John A. Frantz, M.D.

June 26, 2004