Re: wires

["John Hertzman" <johnhertzman@xxxxxxxxxxxxx>]

Beatle Bayly comments on the unfairness of comparing a bicycle wheel to those
on a tricycle or quadracycle, because of lateral stresses on the wheels of the
later, but concludes with "The inventor of the spoked wheel remains, in my
mind anyway, a genius of the first order". Although there were spoked wheels
three millennia before there were wire-spoked wheels, I would certainly tend
to second his thought. I don't have the name of the genius offhand, but the
date was around 1870.

The celeripede, a.k.a. the hobby-horse or dandy-horse, is usually credited to
Nicephore Niepce, better known as a pioneer photographer, in 1816; pedals
connected by con-rods to a crank on the front wheel were added in 1840 by
Kirpatrick MacMillan, and in 1865 Pierre Lallement simplified this into a
crank directly on the front axle, still with wood spokes, iron tires and both
wheels of about the same size. In the 1870 the person or persons whose names I
don't have (at this house, anyway) modified that heavy iron-framed
"boneshaker" into the 'ordinary' or 'penny-farthing' bicycle with rubber tires
and a large-diameter wire-spoked wheel, essentially a monocycle with a small
stabilizing trailing wheel on a light wood or steel-tube outrigger. The rider
sat directly over the front drive wheel, the size of which was limited only by
the leg-length of the rider. This was not terribly safe, especially for a
beginner mounting, or in sudden stopping, and the geared chain-driven
rear-wheel drive 'safety' bicycle, with the rider's weight lower and well back
between two wheels of approximately the same size, was developed in 1876 and
marketed as the Rover by a company which until recently built some very nice
cars under the same name. (With a De Dion rear end, Alfa content, and safety
fuel tank between wheels, also Alfa content, and unfortunately unable to
survive on its own, still more Alfa content)

The important thing about spoke-lacing geometry for sometimes laterally loaded
wheels is that all of the spokes must always be in tension, varying certainly
under degree of lateral loading but still always under some tension, and why
roughly half the spokes are angled in and the other half angled out, and the
spokes are not normally purely radial, but tangent to some appreciable hub
circle, and the entire rim always in compression all the way around, which is
the main reason minimum-weight light-alloy rims normally have greater numbers
of spokes.

Cheers, though ready to be banished,

John H.
--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided