Stans ate my rim?

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Stans ate my rim?
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Posted: Apr 16, 2021 at 16:20 Quote
Well I was prepping my bike for this riding season to discover this under the tubeless rim strip. The aluminum was crumbling under the pressure of my fingers. Lots of other spots showing evidence of corrosion.

I've heard stans sealant can cause corrosion like this, but never dreamed it would actually happen. Is the sealant really the culprit or could it have been something else I did?

I have never used any solvents or chemicals to clean the rims, always used good old fashion elbow grease. Time to replace another rim or safe to squeeze out another season, thoughts?


Posted: Apr 17, 2021 at 0:50 Quote
I'd speak to the rim manufacturer!

Posted: Apr 17, 2021 at 2:06 Quote
Ya, I have never ran a sealant other than Stans and never seen any type of corrosion on my Alu or carbon wheels. This is a crazy photo.

Posted: Apr 17, 2021 at 6:06 Quote
JonnyTheWeasel wrote:
I'd speak to the rim manufacturer!

Thought about it, but these spank rims are outside any warranty period. I already suspect that will say not to ride the rim to cover their butts.

I pulled the other wheel apart since this post. On the other wheel, I switched to orange sealant because I battled some tire damage and needed sealant in pinch and that's all that was available. I continued running different sealant front and back for a few years. There is not a single sign of corrosion on the orange sealant rim!

Posted: Apr 17, 2021 at 7:45 Quote
Water, salts, limestone dust, etc., are all more likely culprits. I rode with a group years ago that rode across a certain creek that literally ate up everyone's rims on two crossings. I missed that ride for some reason and rode the area years later, I remembered to cross the creeks bare footed. Grease the nipples next time maybe?

Posted: Apr 17, 2021 at 8:55 Quote
Mountainfrog wrote:
Water, salts, limestone dust, etc., are all more likely culprits. I rode with a group years ago that rode across a certain creek that literally ate up everyone's rims on two crossings. I missed that ride for some reason and rode the area years later, I remembered to cross the creeks bare footed. Grease the nipples next time maybe?

It’s corroding all over the rim not just around the nipples. I would at least contact the manufacturer to see if they have an explanation. Maybe they don’t replace it, but might give you an idea how to avoid it on the next set. I would not be surprised if the choose to warranty or give you a deal on a new set.

Posted: Apr 18, 2021 at 7:57 Quote
So the water is not getting in at the nipples, but through the bead of the tire? Then how does the water get in under the tape, osmosis? It's not the sealant, and the manufacturer will tell you what I have stated. Greasing the nipples will prevent water from entering the rim, the same as when air escapes from the tire when the rim tape no longer seals. Think again mate.

Posted: Apr 18, 2021 at 9:51 Quote
what kind of spoke nipples did yo use? were the spokes/ nipples also corroded?

The propylene glycol in Stans can certainly contribute to corrosion. If the sealant had leaked under the tape at some time, and then contacted moisture .... its totally possible. there are a pile of other factors that people have mentioned that can also contribute to this type of corrosion.

Its probably best to take the tyres and rim tape off at the end of the season... Its often recommended to prevent barnicle build up over the off season, and save your tires from flat spots / weird sidewall cracks ... preventing corrosion would be another benefit I guess.... that said I am just as bad as the next guy when it comes to end of season maintaince.

shitty deal all round there bud.

Posted: Apr 18, 2021 at 10:25 Quote
The nipples were brass and show no signs of erosion what so ever. All the signs are on the inside of the rim.

I suspect the only way water got in there was when I used some soapy water to help seat the tire the first time. I strongly suspect that some water got in and snuck in under the tubeless strip, reacting with the stans, and massacred the rim.

Thanks for chiming in everyone

Posted: Apr 18, 2021 at 10:29 Quote
Does Stan's not contain water? I was under the impression there's water already in the product formulation; if so, additional water mixing with the product would be of no consequence.

Salt would be a different matter, though. If there's a chance salty water from salted winter roads got in there, I could see the salt causing a problem. I've had to replace fork lowers from Galvanic corrosion at the dropouts. Magnesium is more reactive than aluminum, of course, but salt is my guess.

Posted: Apr 18, 2021 at 11:04 Quote
R-M-R wrote:
Does Stan's not contain water? I was under the impression there's water already in the product formulation; if so, additional water mixing with the product would be of no consequence.

Salt would be a different matter, though. If there's a chance salty water from salted winter roads got in there, I could see the salt causing a problem. I've had to replace fork lowers from Galvanic corrosion at the dropouts. Magnesium is more reactive than aluminum, of course, but salt is my guess.

I am not scientist ... but there are some interesting discussions on other boards (mostly roadies its seems) who have given way more thought and care into the subject...

from a non bike related discussion on the corrosive properties of propylene glycol

"Even with a glycol solution in distilled water, both ethylene glycol and propylene glycol form acidic compounds under oxidation. This becomes corrosive on wetted surfaces and forms organic acid byproducts."

https://www.designnews.com/automation-motion-control/fighting-corrosion-cooling-loops

Posted: Apr 18, 2021 at 11:14 Quote
Salt water from winter roads could indeed be the source... but looking at your avatar: do you ever ride on the beach, or cross brackish water streams near the beach?

To me it also seems to be coming from outside the rim, via nipples towards the holes in the rim bed.

Posted: Apr 18, 2021 at 11:19 Quote
cmcrawfo,

Interesting. Thank you for the link. Other possibly relevant passages:

"Anodization [ ... ] forms a layer thicker, by orders of magnitude, than the thin natural passivated layer that forms on exposed aluminum. The natural layer is not an effective barrier against corrosion, but an anodized layer can be, provided moderate pH levels are maintained and halide ion concentration remains low."

"In a low velocity area, a pit can form due to the localized high concentration of a corrosion agent such as halide ions. Once formed, the rate of corrosion in the pit accelerates due to the volume within the pit not exchanging fluid with the rest of the fluid volume, resulting in ever increasing concentrations of corrosive ions and the expansion of the pit.

Damage from this type of corrosion is particularly dangerous, as it occurs with little observable effect on appearance or performance, with the corrosion affecting only a small portion of a surface. The corrosion, however, propagates deeply into the metal and can create leaks with no warning.

As with other corrosion forms, high halide concentration, especially in the presence of oxygen and higher or lower pH levels, will create ideal conditions for pitting to occur in aluminum or steel. Stagnant flow locations should be avoided, and corrosion inhibitors for removal of oxygen can be added."

Posted: Apr 18, 2021 at 11:26 Quote
Grumposaur wrote:
Salt water from winter roads could indeed be the source... but looking at your avatar: do you ever ride on the beach, or cross brackish water streams near the beach?

To me it also seems to be coming from outside the rim, via nipples towards the holes in the rim bed.

If you look at other images of tubless rim corrosion, this corrosion patter looks nearly identical.

that said... road salt and industrial pollution would be more likely than salt/brackish water in London On.

Posted: Apr 18, 2021 at 11:46 Quote
I wasn't aware of the OP's homeplace. Just from experiences with MTB or MX bikes used at beach races in the floodline on North Sea sandbeaches look almost terrible instantly.

I never saw anything more than superficial before on rims, such a large crumbled area is new for me. Therefor my hunch is outside influences. Getting in to rim and building up in the edge around the holes and corroding over time.

But would you suggest that it is caused by seeping sealant under the tape and near the hole it contacts fresh air for corrosion? If air/oxygen doesn't play a role then why is it only occurring around the wholes?

I'm now googling for it and indeed such bad cases happen more...Eek

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