Jim’s Tech Talk
By Jim Langley
Orange Seal’s line of sealants for tubeless bicycle tires was the big story last week. If you missed it, here’s the link: Quick Product Tip: Orange Seal’s Line of Bike Tubeless Tire Sealants now Includes Subzero.
As far as I can tell, tubeless tires haven’t caught on for road bicycles the way they have for mountain bikes. But what does seem to be catching on is road riders getting and using gravel bikes. And tubeless tires are almost as common on G bikes as they are on MTBs.
So I want to share a couple of comments to last week’s story. I’ll add some thoughts. Please share yours too.
Another Way to Get Sealant Inside When You Don’t Have Removable Valve Cores
It’s easy to pour or inject tubeless sealants into tubeless tires because most tubeless valves have removable cores. But you might want to put some inside a tube that doesn’t have a removable valve core. My low tech suggestion for that, that I mentioned last week, was to poke a hole in the tube, insert the sealant and then patch the hole.
Well, Brian Nystrom was kind enough to offer a different method. He explains:
“There’s another way to inject sealant into tubes or tubulars without removable valve cores. It seems a bit involved, but it’s actually pretty simple in practice and it works:
1- File off the flared end of the valve core threaded rod.
2- Remove the nut.
3- Pinch the tube/tire below the valve stem and allow the core to drop down until you can hold it.
4- Inject sealant (photo courtesy of Park Tool)
5- Push the valve core back in place and reinstall the nut.
6- To prevent the nut from possibly coming off on its own, either:
a- Use a valve cap
b- Put a drop of glue on the end of the threads. You can remove it next time by unscrewing the nut.
c- Lightly peen the end of the valve core threaded rod with a small hammer or just about any metal tool. It’s brass, so go easy.
If the valve core happens to fall into the tube/tire, don’t panic; it’s pretty easy to find it by feel and maneuver it back into place. Of course, it’s much easier to buy tubes and tubulars with removable cores in the first place.”
Thanks for the tip Brian! Speaking of easier ways to get sealant, I’d like to add that there are tubes that already have sealant in them. Slime make these for example: https://amzn.to/47Uxzd1
Does sealant corrode aluminum rims?
Reader “syborg” brought up the issue of corrosion in aluminum rims possibly caused by sealants saying that, “I used to be an Orange Seal fan until the day I discovered that my aluminum rims were corroded and had to be retired from use. A friend that I turned on to Orange Seal had the same thing happen to his aluminum rims. They claim it is non-corrosive, but that’s not my experience.”
To this, Brian Nystrom said, “It may depend on the anodizing on the rim, or lack thereof. Un-anodized rims would likely be more prone to corrosion.”
“Big Ring Bob” added “I think the issue with corrosion relates to a stem that IS NOT aluminum making contact with the aluminum rim. A chemical reaction occurs when dissimilar metals make contact called electrolysis. The stem might be aluminum and the nut could be a dissimilar metal and create the same problem. The ammonia can hasten this process. Stan’s is reported to have the same problem.”
Since tubeless tires first appeared on bikes there have been reports of sealant causing aluminum rims to corrode – the theory being that there’s ammonia in sealants which attacks aluminum. Like Big Ring Bob pointed out, Stan’s took a lot of heat about this online.
It took a little digging but I finally found Stan’s Q & A where they give an official response. It reads:
Q: Do you add ammonia to your sealant and is it bad for my tire and/or rim?
A: We use natural latex in our sealant and a small amount of ammonia is added to natural liquid latex as a stabilizer when harvested. While there may be a strong smell when initially opening your bottle, this trace amount of ammonia will continue to off-gas over time and the smell will fade. This very small amount in our finished sealant formula will have no damaging effects, even after years of use. Although our Yellow Tape may not be necessary to seal your rim, you may add one layer to protect un-anodized or scratched areas of your rim from oxidation due to moisture in the sealant.
[Editor’s note] Orange Seal also uses natural latex for their sealant.
Stan’s answer mentions protecting un-anodized or scratched areas of rims (anodization removed). But they say it’s to protect the rim from the moisture in the sealant, not the ammonia.
Big Ring Bob offers that if dissimilar metals are used, electrolysis can occur. That’s a common problem with aluminum seatposts, causing them to freeze via galvanic corrosion inside steel frames (aluminum stems inside steel forks too).
However, most tubeless stems are made of aluminum as are the valve nuts, so they’re not dissimilar metals meaning they shouldn’t corrode on their own.
So if it’s not the sealant, what’s causing the corrosion? My best guess is that Big Ring Bob is on the right track. But I don’t think it’s dissimilar metals. I think it’s salt that’s attacking the aluminum. Both salt in the air and water can cause aluminum to corrode.
I’ve seen this in the form of white flaking corrosion on the stems and crankarms on bikes of riders who sweat profusely. And I’ve actually ruined one set of drop bars this way riding thousands of miles on an indoor trainer where you drip constantly. I was replacing the handlebar tape and realized the anodized aluminum bars were completely corroded and unsafe to use anymore.
But I can’t explain how sealant or tires take in salt. I know roads are salted in some parts of the country (and that salt attacks cars) but how it could get inside bicycle tires and eat aluminum rims I have no idea.
Please weigh in with your theories and maybe we can solve the mystery of how aluminum rims corrode. Personally, I have never had any tubeless aluminum rims damaged by Stan’s, Orange Seal or any other of the many sealants I’ve used in road, mountain bike and gravel wheelsets.
Jim Langley is RBR’s Technical Editor. A pro mechanic & cycling writer for more than 40 years, he’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Tune in to Jim’s popular YouTube channel for wheel building & bike repair how-to’s. Jim’s also known for his cycling streak that ended in February 2022 with a total of 10,269 consecutive daily rides (28 years, 1 month and 11 days of never missing a ride). Click to read Jim’s full bio.