What’s this stuff coming out of my (bicycle wheel) rim?

Took the valve out of one of my road wheels to put another layer of tape on and a load of this powdery stuff came pouring out. I managed to get a lot out but I can still hear some sloshing around the rim cavity. What is it? Dried sealant? Shouldn’t be there. Alloy corrosion? Dried tape residue? My best guess.

Gorilla tape, alloy rim, unknown nipple material (factory wheels).

What does it taste like?

Crushed up rhubarb and custard sweets and childhood disappointment.

Sherbert. Probably lemon.

(looks like alloy corrosion)

Alloy or carbon rim?  If it’s hard and crumbly, it’s possibly alloy corrosion, but that’s a lot of material (especially if a carbon rim).  If it’s soft and crumbly, I’d suggest it’s some combination of the tape, water and sealant.  If it’s a carbon rim and there’s a decent cavity, it could be that it’s part of the mandrel used to form the wheel and hasn’t been properly removed and is no breaking down.

Alloy rim.

It’s quite dry and crumbly, but rubbing it between my fingers leaves them feeling slightly sticky, which makes me think not corrosion. Think it probably is the dried adhesive from the back of the tape over the spoke holes. Never noticed this before though and I’ve always taped rims with Gorilla tape <shrug>

I’ve had mud and sand get into the rim void. It’s only the really fine stuff that gets in and dries to a powder.

I have had similar when on wheels that have been taped with gorilla tape, but never on rims that haven’t. Gorilla tape is porous isn’t it? See https://www.singletracks.com/mtb-gear/why-gorilla-tape-isnt-ideal-and-other-mtb-tubeless-taping-tips-with-drew-esherick-from-stans-notubes/#:~:text=He%20mentioned%20that%20sealant%20slowly,proper%20tubeless%20tape%20isn’t.

Nice.

Is tubeless tape really so expensive that people are willing to use cheap alternatives? I’m a right skintflint, but I have a drawer full of different widths of proper tubeless tape.

I should’ve stayed with Mavic wheels, then I wouldn’t have needed it.

@nixie

“He mentioned that sealant slowly evaporates through the thick black tape just like it does through the weeping sidewalls of tires because Gorilla tape is porous — where a proper tubeless tape isn’t. That evaporated sealant then enters the inside of your rim, which isn’t anodized and speeds the corrosion of the rim and aluminum nipples.”

My back wheel developed a quite loud, distinct rattle coming from the rim. Now it’s stopped.

I had a surprising amount of mould inside alu handlebars which was probably caused by a tiny amount of postit note glue and water. Didn’t look like yours though, was fluffy.

Maybe combination of sealant, tape glue, and tiny mud/sand grains that came in via muddy water?

Have you tried snorting it?

Did all your mates think you were a dickhead despite you have a great time?

Were the wheels it came out of off a Delorian?

Can you post it to me?

Yea I think gorrila tape leaks after a while, and probably causes problems like this

Annoying, as it is by far the easiest tape to install ime

You’ve discovered a portal to Breadcrumbia

Fairy dust? Sprinkle it on something to see what happens. Or maybe angel dust?