Crack in back wheel at nipple. Is it still safe to use?

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by VTR1000SP2

So I just noticed this stress crack around the nipple hole next to valve hole on my back Alpha 340 1st Gen rim, I say 1st Gen as it was the lighter version before the current version. It is holding a nipple that attaches to a drive side spoke.

I'm heading to Mt Mitchell next week and wanted to run these but won't if it's not safe.


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by alcatraz

Isn't the wheel already impossible to true?

I don't think the wheel will fail. I can just imagine the brake rub, especially when out of the saddle must be very annoying.

I guess I would maybe release tension there half a turn and add a quarter turn on the neighbouring DS spokes. The wheel will go out of true radially but should be rubbing the brakes less.

I'd like to add I'm an amateur.

Maybe the crack there acts as a structural weak spot that can lead to a kink of some sort and possibly cause sudden instability. I'm curious to hear what wheelbuilders have to say, hopefully with an explanation.

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by bikerjulio

I'm only an amateur wheel building person. And I do have a set of first gen rims like those.

My advise would be to trash it and don't even think about it.

You could rebuild the wheel with a new version rim, but don't use that. Nipple washers on the DS next time.

Depending on spoke count, the wheel will either become unrideable or at least develop a severe wobble when that lets go. Which won't be too much longer.
There's sometimes a buggy.
How many drivers does a buggy have?


So let's just say I'm drivin' this buggy...
and if you fix your attitude you can ride along with me.

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by Hellgate

Time for the recycling bin. It's trash.

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by VTR1000SP2

Thanks guys. It'll stay on the indoor trainer bike for now. Will build another rear to match the front.

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by WinterRider

Hellgate wrote:Time for the recycling bin. It's trash.

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--->Alpha 340 1st Gen rim.......... Anyway to determine the DS tension.. know someone with a spoke tension meter?

I've only seen 2-3 spokes pull thru NOT via some interference dropping into the spokes.. say like the derailleur on the cheap box store bikes. In each case the DS tension was 150 kgf or higher.
Last edited by WinterRider on Thu Jul 13, 2017 12:39 pm, edited 1 time in total.

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by glam2deaf

I had the same problem, except mine happened while riding. Also happened to be about 60km into the country side... Luckily I have a lovely mother who didn't have anything better to do that day. It was also a good lesson to check my gear more often.

The rim is trash. I had much better luck with the 400s If you want to stick to Stans.

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