Wheel spokes are probably the most overlooked part of the bicycle, and with good reason. Nobody really knows what they’re for. Most people think that spokes are there as a support structure for the wheel, which is correct, even though it’s an oversimplified explanation. It’s actually a highly intricate support system, with rods of uniform length, loaded strategically at a radial distance
from the circumference of the wheel. The weaving geometrical pattern of the spokes has a significant effect on the performance of the bicycle, and modified spokes produce different effects.
In And Out The support given by spokes is so misunderstood that even the way theyâ€™re perceived to behave is wrong. When asked about wheels, most people will reply that the support structure is an outward push given by spokes. In reality, spokes donâ€™t push outward at all, but rather pull the wheel in. When a rider pushes down on a pedal, the force goes to the chain, then to the hub of the wheel. From the hub, spokes at the front of the wheel pull down on the inner circumference of the wheel, and then pushes the force out when it makes contact with the ground, resulting in forward motion.
Acting as One The wheel is so dependent on the internal structure of the spoke pattern that if just one spoke failed, it would cause an imbalance in the lateral force applied to the wheel circumference. The imbalance would cause lateral buckling in the wheel, or cause other spoke to fail due to the added force.Failed spokes are also highly dangerous, if a spoke were to fail while the wheel is moving, it could snag on the chain and cause a collision.Spoke patterns affect wheel performance in areas such as energy absorption, mass, and stiffness. Contrary to popular belief, spoke patterns arenâ€™t determined by the number of spokes installed in a wheel, but by the number of times a spoke crosses with another spoke. This is because loner spokes, which are tangential to the hub of the wheel, need a wider diagonal fieldcausing more crossings.
Length and Weight Analysis has shown that spoke length has no impact on normal riding, but have noticeable advantages when wheels start carrying imbalanced loads. Whenever a bicycle corners, the weight shifts, causing a stark lateral difference in stress patterns that longer spokes are better equipped to deal with.
RESOURCES: http://yellowjersey.com.au/page_1-Home-of-Yellow-Jersey.htm http://www.exploratorium.edu/cycling/wheel2.html