ted_major

I was just taking apart a front wheel to rebuild with a hub dynamo, and found what looks like powdery white corrosion around one of the spoke holes:

Rim with corrosion around spoke hole

How concerned should I be?

To fill in the details, this is a wheel I built in 2017 for a drop bar conversion on an old MTB. (Alex Adventurer2 rim, Shimano Deore hub, Sapim Race spokes, Stan's tubeless rim tape). The clearance on the old frame with Rat Trap Pass tires was a little tight for comfort, so I returned it to original condition and removed the wheels after a couple of hundred miles. Since then, they hung in the shed (out of the weather but not climate controlled) until I brought them out of retirement for a Long Haul Trucker frame I picked up in early/mid 2020. They haven't been ridden in the rain, and currently have about 650 miles.

Is this apparent corrosion reason for concern? Is there anything I should do to prevent further corrosion?

Moe Zhoost

If you had a significant problem, I'd suspect to see evidence of corrosion on the outside as well. And with multiple spoke holes, not just one. I'm not sure what your picture shows but I wouldn't be much concerned about it.

Iride01 

Corrosion? Where?

If it's there it's not bad enough to be anything. Just clean it up, put it all back together and ride.

You wouldn't believe the rusty steel rims many of us use to ride.

HillRider

Were these rims set up with tubeless tires? Maybe some of the sealer got under the rim tape and dried and that's what you are seeing.

ted_major

The powdery white stuff around the spoke hole. It looks kind of like what happens when an old alkaline battery leaks inside a transistor radio.

I’m inclined to clean up and move on, but curious what might have caused it.

Nope, I’m still sticking with tubes.

cjenrick

electric field from dynamo.

to verify, compare rear wheel

sweeks

Be serious.

The white material looks less like corrosion than some sort of paste. If it were actual corrosion, I'd expect a history of several seasons' use on salted roads. Wipe it off and put the wheel back together.

KerryIrons

It could be aluminum oxide, but it's hard to tell from the picture. Remove it with your fingernail and see if the underlying metal is damaged in any way. If you see clean metal underneath then it's not corrosion. If the metal is pitted and thinned, then it is corrosion and should be watched to see how fast it grows.

Iride01 

Could be a many different things. Something getting in around the spoke nipple and dripping down on the backside of the tape over the spoke hole. Your salty sweat, some cleaner possibly you use. Maybe a puddle of water you road through that had a lot of something in it.

Regardless, it's not enough to be the slightest issue. You might just redo your tape again in a year or so and check if it's a continuing thing or just a one time thing.

cjenrick

wheel builder might have used white lithium grease on nipples

and be aware of galvanic corrosion due to dis-similar metals, ie brass to aluminum, nickel to aluminum etc

but looks like steel inserts so maybe aluminum nipples to steel