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Rim splitting at seam- Toast?

Old 03-03-18, 10:32 PM
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Rim splitting at seam- Toast?

Hi guys,

So I went off a sharp ledge on my beater road bike and got a pinch flat. Well, bummer.

On closer inspection it appears the impact happens right at the rim seam, and it is beginning to visibly split. It is still "seamless" at the bottom, but at the outermost edge (toward the brake track) it has separated to approx. .8mm.

Is this unsafe to ride, or can I use it to complete destruction? I'd hate to toss it, but I don't want to crash...

Let the games begin! Lol
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Old 03-03-18, 10:34 PM
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You have already seen complete destruction and have not crashed. Quit while ahead
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Old 03-03-18, 10:41 PM
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Front or rear? Sudden tire/rim failures in front can be excessively exciting. A resulting crash could well be a broken collarbone or the like. I wouldn't ride it. The resulting crash in back, if it happens, is much more likely to be a slide and road rash.

It may never fail. You may just flat and roll to a stop. But be forewarned.

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Old 03-03-18, 10:51 PM
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There's an excellent chance that the rim was always this way. Pinned (non-welded) rims are often made from sections that were cut squarely. When formed into a hoop, they touch at the bottom (where the circumference is smaller) leaving a small gap at the outer edge.

It's impossible to say without seeing the rim, but if the rim is otherwise round, and the impact point isn't within a few inches of the joint, I'd suspect that you don't have a problem.
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Old 03-04-18, 12:56 AM
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Consider all the spokes pulling inwards.
They ALSO pull the rim ends together with considerable force.
Unless someone missed to insert the tab/pin in the ends while making it, the rim won’t/can’t pull apart. Unless the impact did some other damage, like flaring the brake track, flat spotting etc.
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Old 03-04-18, 07:29 AM
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I would suggest having a look at the seam on the other wheel to see how they compare. As dabac mentioned, that joint is under pressure, not tension and is not likely to come apart.
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Old 03-04-18, 09:13 AM
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Thanks for the replies! The issue is with the front wheel. I will compare it with the rear soon.

I could have sworn there wasn't a crack there before. There IS a small inward flaring of the brake track due to impact with a pole while locked about 1/4 inch away from the split.
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Old 03-04-18, 11:31 AM
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Pics
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Old 03-04-18, 11:50 AM
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Originally Posted by squidpuppet
pics
+1!
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Old 03-04-18, 11:56 AM
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Originally Posted by dabac
Consider all the spokes pulling inwards.
They ALSO pull the rim ends together with considerable force.
Unless someone missed to insert the tab/pin in the ends while making it, the rim won’t/can’t pull apart. Unless the impact did some other damage, like flaring the brake track, flat spotting etc.
Not to mention the steel tire beads which also hold the rim together at the seam.

Without seeing your wheel my guess is that you have nothing to worry about.
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Old 03-04-18, 12:37 PM
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Originally Posted by SquidPuppet
Pics
Hold on...
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Old 03-04-18, 01:12 PM
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Here we go....

Danger to life and limb, or nothing to worry about?
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Old 03-04-18, 01:18 PM
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If the wheel is reasonably true, with no serious high or low spot on either side, then it has been that way all along, and you simply didn't notice with the tire mounted.

Keep in mind, that the tire pressing sideways keeps the flanges aligned, while the spokes hold it all in cpmpression.
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Old 03-04-18, 02:19 PM
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How true is the wheel?

I'm going to disagree with FBinNY. It is possible that an impact right at the seam would spring in, and back out, slightly mushrooming the metal around the seam.

In this case, you might be able to feel a bump at the seam.

However, the conclusion is likely the same. If the wheel is true, and you're not getting flats, then you're probably fine. If the brake track bumps, you should be able to touch it up slightly with a file.
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Old 03-04-18, 05:00 PM
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Ok, thanks guys! I'll keep riding it then.

The wheel is decently true and the only flats I get are from my own negligence. If it really isn't about to spontaneously combust then hurray!
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