Broken Spokes

weyless

i need some help here. for some reason i manage to break a spoke about every 2 to 3 months. i have mavic 517 SUP rims with DT champion 14/15/14 DB spokes and shimano deore hubs. the shop that trues my wheels thought that maybe the spoke tension was too tight the first time that they were built. so i got some new spokes and had him rebuild my wheels. he went through and set the tension to where they were not that tight, but sure enough after about 2 months riding on the newly built wheels a spoke broke.

can anyone tell me if there is something else that would cause the spokes to break? any help will be appreciated.

moparchris

hmm, what type and gauge are the spokes ? if the tensions right they shouldnt break.. is the wheel like deformed badly or anything and what were you doing when they broke ?

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GT Ruckus SS
2006 Giant Trance 1
Giant TCR Euro

daveornee

DT Competition (Not Champion) has Double Butted 14/15/14 spokes.
Too high tension does not break spokes... Not stress Relieving is the main cause.
Tension Balancing and spoke alignment are the other techniques needed to minimize spoke breakage. Spokes break due to metal fatigue. Stresses in manufacture of the spoke and building of the wheel need to be relieved. If the spokes have any unsupported bends they will flex during use and fatigue will result in breaking. The highest tensioned spokes carry proportionially greater load so it is necessary to even out tension so the load is spread across more spokes and larger areas of rim and hub.
You didn't mention number of spokes, spoke pattern, or your weight. 32 spoke 3 cross pattern is fairly standard for most riders. Stiffer rims help spread the load as well. Mavic 517 is relatively light, but adequate for lighter riders who keep their tires on the trail (or road) and don't hit big bumps.
Looser spokes make a smaller number of spokes handle the load.
100 kg Force is the standard tension for front spokes and right rear spokes on most wheels.

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David Ornee, Western Springs, IL USA

Ugur

I want to ask another question about broken spokes. I am using a Vuelta rim (don't know the model) with 32 spokes, and I am 83kgs. I realized I had broken 2 spokes when I was on a holiday and after like 50km of ride it was 4.

What I am wondering is untill howmany spokes will that rim withstand a normal race ride?
On that same day I made a 5.5 km descend (3.5 miles) on a rough terrain and the wheels were OK.

Thanx.

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____Ugur H. Tosun____
__METU MTB-TEAM__

daveornee

You can ride with one or two broken spokes on a 32 spoke wheel. The stiffness of the rim and where the broken spokes are in relation to each other will determine how many. However, it isn't good for the rim, spokes, or even the hub to extend your riding with even one broken spoke.
The load is intended to be spread via all 32 spokes. Localized peak dynamic loads are taken up by remaining spokes so the load distribution makes it more challenging for the remaining spokes and thus their pulls on the hub and rim.

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David Ornee, Western Springs, IL USA