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September 16, 2017 4 Comments
You’re building along when a nipple runs out of spoke thread. You feel an increase in friction as unthreaded spoke shaft encounters nipple threads. This can occur with a slightly too long spoke (or too small rim). What to do? Consider turning the nipple further into this stiff zone. Why?
1/ Nipples are softer metal (brass and aluminum) than spokes (steel) and their threads yield with minimal resistance. Also, spoke thread is rolled so peaks are above the spoke surface and valleys, below. When the nipple encounters the spoke shaft, only 1/2 of its thread must yield; far less interference than between two machined threads.
2/ Spoke threading, as with most thread forms, carries the entire tension load on 3 or 4 threads. The rest are available but not load bearing. Driving a nipple down a spoke a few turns past threading has inconsequential effect on load carrying capacity.
3/ Testing shows that nipples support spoke threads. When a few spoke threads are not engaged and when the spoke endures riding induced load cycles, fracture can occur in those empty threads. Full engagement increases spoke fatigue life for thread fracture. It would be an enlightened building strategy that forced all nipples to be turned further so no spoke threads were empty.
Another option is making only 6mm of thread on your spoke so that when it comes flush with the nipple top, spoke threads are entirely embedded in the nipple—a great way to increase fatigue life.
4/ A nipple driven further down a spoke develops friction that helps prevent vibration induced loosening, a good outcome for any hard-used wheel.
Beware of excess spoke protruding from the nipple inside the rim, it may interfere with the tire. Otherwise, please remember the possible benefits of tightening nipples past the spoke threads. Not all bad, in fact, there are some interesting benefits.
Now is a good time to introduce a new product, a better spoke ruler than any before. This ruler is by Pi Spokes, a very interesting project of which you will hear more in the future.
1/ At long last, a ruler marked in 0.5mm increments. These finer increments are easy to read (or ignore). Let’s face it, spokes are not all made exactly to whole millimeter lengths. Builders deserve to round up or down with complete accuracy. Spoke machines like our Morizumi can also cut precisely to 0.5mm so a finely graduated ruler is perfect.
2/ The spoke lies in a groove below the scale so the issue of visual parallax is minimized. Lengths can be more quickly established, even in poor light.
3/ One side is for J-bend elbows, the other for straight pull. The ruler is made of highest grade aluminum, scale is permanently laser etched over bright purple anodizing. Price is $20.
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