Wow, Why didn't I think of that?
Note: Many cycling experts object to the old-fashioned terms "right" and "left". These obsolete terms were in common use decades before the invention of the bicycle, so they are considered too mundane and easily understood. These experts prefer the convenient abbreviations "DS" and "NDS".
Evidently, they fear that their knowledge will get into the wrong hands if written in prosaic standard English. For the benefit of these people and their disciples, this page is also available in DS/NDS format:
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Thanks to modern pharmaceutical science, today's cyclists are stronger than ever. At the same time, the trend to lighter rims and fewer spokes continues.
As a result of the higher stresses and cutting-edge wheel construction, a fundamental design flaw in existing bicycle wheels comes to light. Millions of cyclists are suffering loose or broken spokes usually on the left side of the rear wheel, leading to poor handling at best, or getting left behind by your cycling buddies, or, in more severe cases, injury or death!
Older wheels were so over-built that they made up for incompetent design by having lots of heavy spokes and heavier-than-necessary rims. Even today, most front wheels hold up alright, because they still have more spokes than are needed to cope with the usual loads experienced by front wheels...but what about the all-important rear wheel?
While the right side spokes tend to hold up alright, the left spokes are often left with insufficient tension. If the left spokes are too loose, there's no way that the bicycle can ride right...you'll suffer spoke breakage due to metal fatigue on the left spokes.
Go right now to wherever you left your bicyle, and check the spoke tension of your rear wheel by plinking the spokes and listening to the tone. You'll probably find that the right side spokes are at the right tension, but that the left spokes will be noticeably looser. When you plunk the left spokes you'll notice that the pitch of the plunk is considerably lower than that of the right spokes. Why is this?
Believe it or not, many of the unscrupulous con-artists that are so common in the bicylce industry will try to get you to believe that this is a "feature!" Yeah, right!
They'll give you some spiel about a mystical property called "dish", which supposedly has something to do with the fact that the chain is on the right side. This is, of course, complete nonsense, since the chain never touches the spokes, as long as your derailer is adjusted right.
These idiots must have been left back in school when it was time to study history. Everydody knows that in the early days of cycling, there was a problem with the left pedals falling off.
This was solved by the Wright brothers, when they invented the system of using a left-hand (left-foot?) thread on both the left pedal and the left crank.
You might think that this would not be right, and that the Wright brothers had it backwards, because the friction of the pedal bearings would tend to turn the right pedal to the left and the left pedal to the right. Thus, the right-handed right pedal should fall right out, while the left handed left pedal would be left in place...but it doesn't work that way; instead an interaction with the Earth's magnetic field sets up eddy currents right in side the pedal axles, leading to a tendency for the pedals to tighten themselves, as if by magic.
When Pierre Lallement and Tullio Campagnolo independently invented the bicycle, back in the olden times, they used normal right-handed threading for the bottom-bracket cups. This worked alright for the left cups, but it was discovered that the right cup would tend to unscrew itself in use, unless the bike was left out in the rain, where rust could help to immobilize the threads.
The great British bicycle inventor James Starley cured this problem by making the right bottom bracket cup have left-hand threads, so that, even if it starts a little bit loose, it will tighten itself right up.
The French were slow to pick up on this improved technique, and many Italian bikes are still made with wrong-way threading, but the rest of the world has picked up on this, and the vast majority of bicycles now have bottom brackets that are threaded the right way: right threads on the left side, left threads on the right side.
Like many great inventions, SYMMETRISPOKES seems completely obvious once it has been explained; the solution to the problem of left spoke breakage is, in fact just a simple matter of using a left-hand threading on the spokes that run to the left side of the wheel!
This completely eliminates the precession effect that tends to loosen left side spokes in old-fashioned wheels that use right-hand threading!
Since I'm a practical mechanic as well as an inventor, I couldn't overlook the confusion that having two different types of nipples could cause. I've come up with an ingneious solution to the problem, however:
As an optional accessory item to SYMMETRISPOKES, we are making available special color-coded nipples to help you keep track of which is which. Since SYMMETRISPOKE nipples look just like ordinary nipples, we offer special bright red anodized nipples to fit the right-hand threaded spokes still used on the right side of the wheel. This prevents them from becoming confused with the left-hand threaded SYMMETRISPOKE nipples.
Well, what about it? It is well known that in the Southern hemisphere, the problem of left spokes loosening up does not occur, but rather it is the right spokes that loosen up if left to their own devices.
Hence, cyclists who ride mainly in the Southern hemisphere should use SYMMETRISPOKES on the right, side of their wheels, not the left.
Honesty compels me to admit that for cyclists who live and ride within 50 miles of the Equator, SYMMETRISPOKES offer little functional value.
Cyclists who regularly travel back and forth between the Northern and Southern hemispheres would be well advised to build up two rear wheels, one for use in each hemisphere...however, there's no need to have two front wheels, since the same front wheel will work in either hemisphere simply by reversing it in the fork!
|The Inventor of SYMMETRISPOKES,|
the Geomagnetic Booster, and
POWerwheels, Sheldon "Genius, But Modest" Brown
|George Brown photo|
"Symmetrispokes can easily be called the invention of the year if not the decade, ahead of electronic shifting and airless tires that also both address serious problems confronting the bicyclist today.
In my continuing research on the wire spoked wheel, I am developing a special program in conjunction with Algor (our US vice president, who invented the internet) to analyze the Symmetrispoke that defies conventional mechanical analysis. The use of right hand thread on the right and color coded pimples makes these spokes even more useful than grouping left and right spokes so close together that even a spoke wrench cannot get between them.
Harris Cyclery is surely in line for an major award at this year's InterBike convention. I think they are on the right track. My cycling cap goes off to this effort."
*Guaranteed for the life of the wheel, or two weeks, whichever comes first. This guarantee shall be void if the purchaser uses tires, tubes, rim tapes or valve caps or other accessories not expressly approved for use with SYMMETRISPOKES, nor will it apply to any wheels which have been subject to on-road or off-road use. Void where prohibited, prohibited where void, keep away from children and animals, use only with adequate ventilation.
|Articles by Sheldon Brown and others|