Alu and sealant

[CogitoErgoSum]

Howzit. I am riding a set of Deore XT rims on my (old 2012) dual sus. The rear rim started loosing air around the valve lock-nut. Took it in today, thought the rim tape was defective after I had a new tyre put on some few weeks back. The LBS told me on collecting it that the aluminium has been coroded around the valve hole, and that sealant does this.

 

Is this possible?

 

If so, blerrie crap. I need new rims one of these days.

 

BTW the guys at the LBS did a brilliant job at fixing it. Only time will tell how brilliant

 

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[Eldron]

Yup. Ammonia attacks alu.

 

There are "eco" sealants like Joes Eco which is safe to use in all alu...

[CAAD4]

Check your alu nipples too. There now quite a few sealants without ammonia in.

[popcorn_skollie]

Some time back I remember someone having the same problem.

Also shimano rims if I remember correctly.

Also depends on sealant being used I suppose. 

 

ie...On the stans bottle it says 'non corrosive'

 

http://i.imgur.com/7rsGHHB.jpg

 

Can't really say much else.

I'm sure there'll be some more feedback...

[Christofison]

Howzit. I am riding a set of Deore XT rims on my (old 2012) dual sus. The rear rim started loosing air around the valve lock-nut. Took it in today, thought the rim tape was defective after I had a new tyre put on some few weeks back. The LBS told me on collecting it that the aluminium has been coroded around the valve hole, and that sealant does this.

 

Is this possible?

 

If so, blerrie crap. I need new rims one of these days.

 

BTW the guys at the LBS are brilliant

 

Sent from my GT-I9505 using Tapatalk

I also have an old set of XT wheels that corroded around the valve hole. I'm pretty sure that it's caused by a reaction between the wheel and the actual valve. It depends how bad it is, but if the tape is applied well, then there should be no leaking at this spot.

 

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[CogitoErgoSum]

Some time back I remember someone having the same problem.

Also shimano rims if I remember correctly.

Also depends on sealant being used I suppose.

 

ie...On the stans bottle it says 'non corrosive'

 

http://i.imgur.com/7rsGHHB.jpg

 

Can't really say much else.

I'm sure there'll be some more feedback...

Thanks. Yeah, wasn't aware ammonia to do that.

 

I have never bought, let alone held a bottle of sealant in my hand.

 

Not good news then.

 

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[Eldron]

I also have an old set of XT wheels that corroded around the valve hole. I'm pretty sure that it's caused by a reaction between the wheel and the actual valve. It depends how bad it is, but if the tape is applied well, then there should be no leaking at this spot.

 

Sent from my E5823 using Tapatalk

 

 

Good call! Galvanic corrosion! That'll account for why the valve hole disintegrates so fast!

 

I've seen rims attacked - mostly where the anodising is weak/removed. It has to be the ammonia. Google says it's this reaction: Al³⁺(aq)+ 3NH₃(aq)+3H₂O(aq)<==> Al(OH)₃(s) + 3NH₄⁺(aq)

 

So twofold attack.

 

I'd recommend a really wide rim tape to completely seal the rim off from the sealant (if it's a corrosive/ammonia based) and one or two layers of insulation tape (over the tubeless tape) around valve hole before you push the valve through - that should keep the two metals from touching one another (and make a better seal).