xxxxx
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Posts: 116
Registered: 21-5-2004
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bicycle spoke lacing "error" ?
i just replaced all the spokes on my bicycle. the rims are 26 inches and have 36 spokes each. the holes for the spokes on the rims are not exactly on
the center of the rim, rather they are offset about one millimeter from the center on the left and on the right, alternatingly. supposedly this is to
put the spokes through the rightly offset holes on the rim to the right side of the hub and leftly offset to the left of the hub. which i did
correctly on the front wheel and it looks very neat and correct. however on the rear wheel i put the spokes throught the left offset holes on the rim
to the right side of the hub. now normally because of the size of the cassette of gears on the right side of the rear hub the spokes on the left have
an angle of approximately six degrees and the spokes on the right have an angle of approximately three degrees. this puts greater tension on the
spokes on the right side of the rear hub. now because i was not paying proper attention while i was working the spokes on the left have an angle of
about seven degrees and the spokes on the right have an angle of about four degrees. simple sine cosine tangent calculations indicate the spokes on
the right will require less tension force to maintain the rim at its centered position on the axle. it does appear to be an error because the nipples
of the spokes on the left do not seem to seat perfectly on the hub. however the nipples of the spokes on the right side of the hub seem to be seated
correctly, and since it is the spokes on the right side of the rear hub which break more often and are more incovenient to replace, requiring the gear
cluster to be removed, i wonder if this might actually be an improvement over the standard method.
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Endo
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Registered: 5-1-2006
Location: USA
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Spoke Lacing
When a rear rim is laced it is typical to have the cogset side of the rim with a shorter angle to allow the rim to center in the frame while still
allowing the cogset to take up space at the hub. This is called "dish", a rim with too much dish will have pressure applied to the rim unevenly by
the brakes because the rim will not be centered in the frame. Often it will cause the brakes to squeal or jitter as they are applied because one pad
hits first or the angles are different and the force applied to each side of the rim is not equal. With too much dish in a rim you also see the
higher tension spokes fail sooner, as well as problems with the chain wearing on the spokes/spoke protector when the chain is on the largest gear on
the cogset. Pay careful attention to how your rear deraileur top limiting screw is adjusted or you may wrap it up in the rear wheel.
Good Luck
Endo
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