Ultegra tubeless rim bed corrosion

[shoota]

So I’m looking at buying these 6800 Ultegra wheels from a buddy and according to him the sealant he used corroded the rim bed. The pic is the worst of it, with a small hole through the bed near the valve hole.
Two questions:
1) How structural is the rim bed to these particular wheels?
2) Any reason I couldn’t just tape these and run them?

They’re in otherwise great shape so I really want to use them, but not if they’re just going to disintegrate later.

[robt57]

My Dura Ace 10s Scandiums did this too. I scotch brite sanded it thoroughly and put one layer of Kapton tape, valve, new tires and sealant. They lost air fast before I did this, and 3 years later they are my best tubeless wheels as far as keeping pressure over log periods.

I have been using eBay Kapton tape for years as rim tap for all tubed and tubeless. I started using it mostly due to how shallow the middle wells were on the early tubeless rims. It takes up nearly zero bed height and make for more manageable mountings overall.

I do use one layer of Pacenti Tubeless tape over the 3x kapton layers for tubeless setups FWIW.

[Dave]

I would't buy them and continue to use tubeless, with more water based sealant. It looks like more than surface corrosion to me.

[robt57]

Just noticed the hole eaten thru, not sure I'd revive that...

[shoota]

Just noticed the hole eaten thru, not sure I'd revive that...

How about taped for tubed use?

[robt57]

If you do use this, I'd stick with low PSi use.

What the brake track wear looks like may make use question superfluous...

[ColonelJLloyd]

Well used wheels
Corrosion through the rim bed near the valve hole
Narrow rims

I doubt any failure in the rims is going to be catastrophic, but it all adds up to wheels I probably wouldn't use.

I have been using Orange Seal for years and it's all I've ever used. I have a hard time believing Orange Seal would do that to a rim. Did the owner say what sealant he/she used?

[shoota]

If you do use this, I'd stick with low PSi use.

What the brake track wear looks like may make use question superfluous...

60psi is what I was thinking. Sound good to you?

[shoota]

Well used wheels
Corrosion through the rim bed near the valve hole
Narrow rims

I doubt any failure in the rims is going to be catastrophic, but it all adds up to wheels I probably wouldn't use.

I have been using Orange Seal for years and it's all I've ever used. I have a hard time believing Orange Seal would do that to a rim. Did the owner say what sealant he/she used?

That's the thing, they're almost unused. The brake track barely shows any signs of use at all. I think he said it was Stan's. It was definitely not Orange Seal because that's all I use as well.

I personally don't think the integrity of the wheels is compromised too much, and I plan on using them tubed anyway.

[robt57]

60psi is what I was thinking. Sound good to you?

Send me the PDF waiver and I'll answer that..;)

[gbcoupe]

That looks like a job for JB Weld. Use a plastic rim strip as well.

[slambers3]

That’s just the corrosion you can see. I personally wouldn’t trust that rim, you don’t know where else the sealant got to inside the rim cavity and where else is rotted away. Rims can fail catastrophically from a split rim bed, I’ve seen it a few times. Road rims endure a combination of high pressure and heat- combine that with high speed and you have a dangerous combination.

[dddd]

That’s just the corrosion you can see. I personally wouldn’t trust that rim, you don’t know where else the sealant got to inside the rim cavity and where else is rotted away. Rims can fail catastrophically from a split rim bed, I’ve seen it a few times. Road rims endure a combination of high pressure and heat- combine that with high speed and you have a dangerous combination.

I am having a hard time disagreeing with this.

There is firstly the built-in and conservatively-tested valve-stem hole, having a diameter (and effective length along the rim) of perhaps 8 or 9mm.

Then there is the little corrosion hole, much smaller, but close to the valve stem hole.

Between them is a short "bridge" of metal, tasked with sustaining a tensile load proportional to the tire psi.
There is also the consideration tire width, since as the tire becomes wider the casing tension increases as the pressure remains constant.
And the wider tire's casing pulls outward on the cantilevered rim sidewall, with the loads fed into the bridge of metal that I mentioned.

Now as slambers3 mentioned, we can't know what the reverse side of the rim's wall looks like, and thus can't know how thin that the metal bridge has become. The narrowness and thinness of this bridge is compounded in effect by the stress concentration surrounding any and all corrosion pits and troughs.

Do the math, it's over my head and I don't have any test data to work with.

[AngryScientist]

i would ride those if they were my wheels, but i wouldnt buy them. there are lots of other good, cheap rim brake wheels out there these days.

[gbcoupe]

i would ride those if they were my wheels, but i wouldnt buy them. there are lots of other good, cheap rim brake wheels out there these days.

Good point and agree, wasn't thinking about the purchase part.

[pcxmbfj]

There is a known deterioration problem with scandium (DuraAce) and ammonium (Stan's) sealant.
I had same issue with aluminum Ultegra.
IMO big fail by Shimano in a weak public reveal.

[oldpotatoe]

That's the thing, they're almost unused. The brake track barely shows any signs of use at all. I think he said it was Stan's. It was definitely not Orange Seal because that's all I use as well.

I personally don't think the integrity of the wheels is compromised too much, and I plan on using them tubed anyway.

Unused, maybe but not undamaged.
The pressure of a tube there and at other damaged places, could very well lead to cracks at those places. I'd say save your dough...
There is a known deterioration problem with scandium (DuraAce)

For right above, yes, I agree shimano didn't do their homework when it came to their first tubeless wheels BUT VERY small amount of scandium in these wheels..mostly aluminum.
The main application of scandium by weight is in aluminium-scandium alloys . These alloys contain between 0.1% and 0.5% of scandium.

[Velocipede]

I wouldn't use them. And Wouldn't use Stans'. Toxic Rot is what I've called it for years. Stans' is super corrosive on alloy rims. This happened on a buddies wheel. I am not a fan of tubeless because of this reason and others.

I wouldn't ride it.

[shoota]

I wouldn't use them. And Wouldn't use Stans'. Toxic Rot is what I've called it for years. Stans' is super corrosive on alloy rims. This happened on a buddies wheel. I am not a fan of tubeless because of this reason and others.

I wouldn't ride it.

Well thankfully I only use Orange Seal, and I love tubeless. I certainly wouldn't let this issue dissuade someone from going to tubeless.