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Who is this John Allen?

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Bicycle “design drift” -- have respect for tradition while innovating John S. Allen http://www.bikexprt.com

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Evolution of the bicycle wheel

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Developments since 1895 Rim material: wood, steel, aluminum Quick release Pneumatic wired-on tire Tire width drift Fewer tire sizes, more standardization

Modern evolutionary developments Aluminum rims becoming prevalent Parallel sidewalls for smooth braking Better spoke manufacture Better automated wheelbuilding Dishing issues due to more sprockets Run-flat performance

Advantages of the traditional spoked bicycle wheel Light weight Assembled from components -- huge number of options Not disturbed by crosswinds Quiet Just sufficient strength Structural redundancy Inherently warns of incipient failure Benign failure modes

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An American saying: “Better the devil you know than the devil you don’t.”

Disadvantages of the traditional spoked bicycle wheel Expensive to manufacture and to repair Requires occasional adjustment by skilled mechanic Wind drag could be lower Can pick up objects, leading to crashes

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Improvements? For whom? For the manufacturer For the retailer? For the racer? For the everyday bicyclist?

Cartridge bearing hub Simpler assembly and maintenance Moderately increased initial cost Slightly higher drag Resistance to contamination

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Aero rims Lower wind drag Weight penalty Structural penalty

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Composite materials Can reduce weight Can enable or impede aerodynamic design Problems with reliability

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Disk wheels, formed wheels Can be simpler to manufacture Can reduce air drag Problems in crosswinds No inherent warning of failure Less, or no, redundancy Heavier unless of exotic materials

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To sum up about revolutionary wheels: Look before you leap Engineering analysis may substitute for trial and error Benign failure is important Desirable characteristics depend on customer

Another example: handlebar stems

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Bicycle brake types Spoon brake Coaster brake Drum and band brakes Rim brakes Disk brakes Hydraulics ABS, human and otherwise

Coaster brake issues Reliability vs. chain loss Clamp band Stopping distance Heat dissipation

What’s wrong with this picture?

Cantilever brake issues, V Brake Brake shoe dive under rim Transverse cable snag on knobby tire

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ABS to prevent pitchover Bicyclist can be ABS controller, with skill Attempts at mechanical ABS system Hydraulic ABS might be possible.

Overall summary Innovation should be undertaken carefully. Testing is useful but never exhausts all possibilities. Have respect for what tradition can tell you.

Thank you!