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June 17, 2007 1 Comment
This article, written by Spence Wolf, first appeared in AMERICAN CYCLING, June 1966 (pg. 19). Images by Wheel Fanatyk.
Hand made tires are a necessity for the racing cyclist, and for other cyclists who want the utmost in response and easy pedaling. They are expensive, thin, and vulnerable to the atmosphere and to damage from the hazards of the road. However, their life can be extended considerably by proper care and maintenance.
Racing tubulars are made by winding a fine thread on a drum, much as an electrical coil would be wound. The thread is then coated with liquid latex. After the latex has “set” for a number of hours, the thread is held together by the latex and becomes a fabric. This fabric is cut off the drum on an approximate 45-degree angle and laid on a table with the latex side up, forming a long, narrow parallelogram. This parallelogram is trimmed to proper length and folded in half lengthwise and well rolled. Then the triangular ends are placed one on top the other and rolled, forming the “splice” and making the fabric into a band. If the splicing is properly done you cannot see where it is located. The further procedures necessary to completing the tire do not concern this article. What is of interest is that the fabric is not vulcanized, but is held together by the air-dried latex. Latex is readily dissolved by petroleum (and other) solvents and nothing containing these solvents (such as rubber cement, oil, gasoline, etc.) should be allowed to touch the fabric of the tire. Using gutta (rim cement) to hold the tire on the rim is all right because the tire’s rim tape protects the fabric of the tire from the gutta.
The outer surface of the sidewalls of road tubulars is coated at the factory but this coating is of course thin and does not take long to wear off, exposing threads to the atmosphere. Attempts to remedy this by applying shellac to the sidewalls are not satisfactory because the shellac is brittle and will flake off. To apply rubber cement is to invite disaster because it merely hastens the breakdown of the latex, causing the threads to separate. The best overall sidewall protection is natural latex.
To prepare the tubular for the latex, first inflate it on a wheel and wash it thoroughly with dishwashing detergent and water. Then rinse thoroughly with water.
When the tire is dry the sidewalls are ready for the latex. I have found that the best brush to apply latex is an acid brush (used in soldering) obtainable at most hardware stores. Wash the brush before using to remove any oil it may contain, and of course use the brush for no other purpose. Keep the tubular inflated until the latex is dry, which takes at least 24 hours.
Shake the latex well and dip the brush only into the “suds,” this will assure that you do not get too much latex on the brush. Therefore, you will be better able to apply a thin coat (which is all you want) to the sidewalls.
If the latex will not foam, add no more than one tablespoon of sudsy ammonia per quart of latex. If the latex is too thick it may be thinned with distilled water. Brush on the latex rapidly being sure not to brush it out too much.
After the latex has been applied allow the inflated tire, on the wheel, to remain in a warm room for 24 hours. Then dust the sidewalls with talcum powder to “kill” the stickiness, and the tire is ready for use.
Portions of fabric taken from old, high quality tubulars can be used for boots (internal reinforcements). All boots, repairs to the fabric, and the sticking down of the rim tape and tread strip should be done with latex. Solvent rubber cement should only be use for repairing the inner tube.
Wheel Fanatyk note: I don’t guarantee the results you may have following these instructions. Spence Wolf spoke from experience, as he was one of the only Americans to seriously undertake tubular tire manufacture (in the early 1960’s). So, proceed at your own risk. Also, tubular tires today are made by a number of companies using different techniques. This article describes typical, historical methods and doesn’t apply to all brands and eras.
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