Bicycle Mechanics - are spokes supposed to cut into each other?

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sqroot3
06-22-08, 12:05 AM
are spokes supposed to cut or wear into each other? i just noticed on my ultegra hubs + open pro's when i was cleaning my bike that there's a little dent in each spoke where it crosses another. i don't know how long ago these were laced because i got them used with a used bike.


jaxgtr
06-22-08, 06:07 AM
moving to mechanics

FlatFender
06-22-08, 06:40 AM
sounds normal.


CrankyFranky
06-22-08, 08:00 AM
are spokes supposed to cut or wear into each other?
If the wheels have a lot of hard miles on 'em, and there's just a little wear, then it's normal. Otherwise, the spokes may be slightly too slack or else the wheel was loaded beyond it's design capacity (meaning rider way too heavy, spokes too light, etc.). Even with this wear spot, the spoke will hardly ever break there but rather at the head end.

sqroot3
06-22-08, 08:22 AM
thanks...I should post here more often!

operator
06-22-08, 08:55 AM
thanks...I should post here more often!

A good handbuilt wheelset will have spokes "bent around" each other so that they run straight: http://www.sheldonbrown.com/wheelbuild.html

dabac
06-22-08, 10:32 AM
A good handbuilt wheelset will have spokes "bent around" each other so that they run straight:
Nah, that's not it. If you lace the wheel with the most common over-under then the spokes will touch at the outer cross regardless what preforming you've done. Run such a wheel at heavy loads or slightly low tension you will eventually get rubbing.
It IS posible to lace wheels w/o an over-under at the outer cross, but it's rare and somewhat frowned upon.

sqroot3
06-22-08, 10:45 AM
Run such a wheel at heavy loads

yikes...I hope 160 doesn't count as a heavy load. the previous owner didn't look that beefy, either.

dabac
06-22-08, 11:00 AM
yikes...I hope 160 doesn't count as a heavy load. .

Well, as posted there are different reasons that will lead to the same result. Mid-to-average rider on a poorly tensioned wheel or a heavy rider on a well-tensioned wheel will both cause the spokes to go slack to some degree, and when they loose a little tension they'll fret and vibrate against each other.

Mr. Fly
06-22-08, 11:12 AM
Although they look like rigid structures, wheels are dynamic in that their spoke tensions change and the rim deflects from circular with each load cycle. Thus, the spokes do move (albeit on a very small scale) and rub against each other during normal service. Over a very long time, the rub marks show up as notches on the spokes. The wheel does not need to be overloaded nor does the spoke tension need to be below a certain range; correctly built and spec'd wheels still exhibit this phenomenon.

Thankfully, these notches do not limit the life of the wheel. Quality, correctly-installed spokes had been reported to give service exceeding tens of thousands of kilometers, over many repacking of the hubs and over multiple replacements of the rims. In other words, don't worry about it. :thumb:

Check out Jobst Brandt's The Bicycle Wheel (http://www.amazon.com/Bicycle-Wheel-3rd-Jobst-Brandt/dp/0960723668/) for a lengthy and thorough discourse on spoked wheels.