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The
Quest for the worlds lightest bicycle
The
under 4 lbs (1818 gram) bicycle
(Please click on a photograph to enlarge)
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Please note that unlike most vehicles shown on this website, the bicycles, named "project 1818" shown here, are design and engineering mockups and have not been constructed to a finished product, and thus, they have not been put to the full road test. Date of this writing: September 16, 2006. Designs from 2003/04. |
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The
Quest for the worlds lightest bicycle Purpose: The goal of this design construction project was to create the lightest practical bicycle. The lighter the bicycle, the easier, it is to operate and potentially the faster and farther to travel, in a given time period. Issues: The major issues in designing a super light weight bike is the weight of the wheels, tires, drive components (crank, pulley's, drive belts or chains or drive shaft), and the wight of the frame. In addition, the craftsmanship and engineering in key areas are essential to minimize energy loss do to friction and excess wight. These include the machining of the wheel bearings, the minimal wight of the frame and the choice of ultra strong but non-conflicting materials. After studying a number of existing light weight bicycles, I noticed that some of the bicycles used expensive lightweight materials, such as carbon fiber, which, under certain circumstances, can be made very strong, but because of the way that these bicycles were constructed, the designs did not take advantage of the unique properties of carbon fiber. Thus in some cases, excess carbon fiber material was used, and in other cases, not all the potential stresses were considered and the bicycle had the potential for catastrophic failure of the carbon fiber. In other cases, I noticed that the bicycles used mixed metals, such as steel and aluminum. Such use of mixed metals can create galvanic reaction or battery effect with the intersection area of the two metals gradually being compromised do to rapid corrosion. It is interesting to note that I have also observed the same flaw in a very expensive Italian automobile design. Had the company taken precautions to shield the mixed metal body, the sports car would not have been prone to such rapid rusting. The stress and strain on the crankshaft and the frame, is enormous and these components must be strong enough to endure high loads, hour after hour. Solution: Unfortunately, the solution to the issues outlined above is not simple. Extremely or ultra light weight materials capable of enduring the huge physical forces either do not exist today or can not be readily engineered into a structurally sound bicycle light enough to achieve and break the 1818 gram / 4lbs weight goal. One method employed, that was not completely satisfactory, was to form the frame out of lightweight Styrofoam, with a thin hollow steel (yes steel) rod in the center. The Styrofoam itself was covered with a thin layer of carbon fiber material. This created an incredibly light "frame". The steel rod served several purposes including to provide a certain degree of stability, to maintain shape in case the carbon fiber - Styrofoam frame failed and equally as important, to serve to hold the wheel bearing housing and to provide and anchorage point for the necessary piano wire stress and strain cables, which stabilize the frame to the steering column and seat column. In the photographs above, the bicycle to the left was lighter than the bicycle to the right, however it was found to be very unstable and ran a constant risk of falling backwards. To alleviate this, the bicycle to the right was designed to have a non-drive small rear free turning wheel. I suppose under strict definition, this should be referred to as a tricycle variant. The free turning rear wheel solved the instability and in fact made the "bicycle" feel substantially stronger. The wheels were stripped down to a level of just adequate, with the tires glued on to a "rimless" rim. Additional Design Information Available A fair amount of unique information was gathered through careful design, testing and trial and error and many existing mistakes and flaws were uncovered during this process. If you are a manufacturer of bicycles, motorcycles or specialty cars, you may wish to contact this designer. The author of this article can be reached by email at "bicycle at didik.com". To control spam, which recently has reached the level of thousands per week, please summarize the purpose of the email, in the heading such as "bicycle design" or "cycle engineering" or "can you help with our bicycle design". Thank you. |
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