Aluminum Nipple Corrosion In Carbon Composite Rims 

I work in the marine industry with carbon composite structures and aluminum structures. Galvanic corrosion is a major concern. We always use an isolator compound. Check out duralac, lanocote, or tefgel. One of these is likely your best option due to the need for assembly and I assume tuning. If you don’t need to service the spoke nipples in the future, you could also use an adhesive with bond line thickness controller beads mixed in. They are 5-15 thousandths in diameter and help ensure the bond line thickness. That provides enough isolation to prevent any galvanic corrosion.

Hey Bill, thanks so much for producing this. There is more chemistry here than is digestible by most people, myself included :) But it's great to see the issues set out comprehensively. Nipple washers are the best available current solution (or brass nipples). There is so much cycling related bulls**t out there, some with literally millions of views - your work is deserving of many more viewers, but of course it's not fashionable enough for that!!

Hello guys i work in a military aircraft worldwide industry and i can see everyday how to install alloy rivets in carbon fibers , we use chromate sealant between the rivets and holes it is called "wet installation", sealant isolates alloy rivets , a suggest add a stainless steel washer CRES corrosion-resistant steel under the nipple head to prevent this kind of corrosion and washers improve rims streght.

Well done, this is very consistent with the stuff we see in our workshop too. On a similar note, carbon fiber seatposts can react the same way in presence of an aluminium seat sleeve

Nice presentation. Aluminum rims and problem is solved.

Thanks Bill for the well done engineering analysis. We also have had issues in Salt Lake City with AL bearings in carbon cups. So the Al nipples are not the only issue. You asked for suggestions: --1. Store the bike in a dry even temperature area to eliminate galvanic corrosion. This requires a relative humidity of less than about 35% and an even temperature to eliminate condensation. No electrolyte (water) and there is no galvanic corrosion. --2. We're in Arizona not far from where airlines store their aircraft so galvanic corrosion is a location related issue. The opposite end of the spectrum from AZ might be storing a bike in Florida where it is humid and compounded by living near the salt water sea. --3. I wonder if using a dielectric grease between these AL nipples/bearings will mitigate galvanic corrosion? We're trying this approach because dielectric grease is non-conductive and perhaps somewhat like the shims or washers you suggested in the video. --4. Don't tighten spokes to unreasonably high tensions. Instead build wheels to the mission. A higher spoke tension does make wheels stiffer. We're experimenting with lower tensions in the 65 to 90 kg-f range and seem to be having good results for recreational mountain bike riders on green and blue trails. This mitigates wearing through the nipple anodizing. --5. In warm wet climates, galvanic corrosion with expensive light weight carbon bikes may be unavoidable so in this case, consider the nipples as a sacrificial anode saving the rim, spoke and hubs from corrosion damage. Al nipples are inexpensive and replaceable. Learn how to re-lace the wheel. LOL Your research is ground breaking. Thanks, James B Frantz

Wow...crazy. I have $2500 Bontrager XXX Kovee wheels that have corroded big time. I brought front wheel to the Trek shop less than a year ago with a busted spoke and they rebuilt the whole wheel. I was inspecting their work after I decided to tape my wheel. I saw several corroded nipples! I squeezed the worst spoke and SNAP! Then I inspected the rear wheel which is 3 years old and they were all corroded. Ugh.

Great video, thanks! I regularly run into issues with aluminum nipples on any wheels, not just with carbon rims, I believe based on the galvanic corrosion between the stainless spoke and the aluminum. I do have a question about the use of washers though - since the washers are metal, don't they maintain the conductivity between the rim and nipples? I can understand how washers spread the loading to the rim, but I would expect that at least some of the anodizing on the nipple would. be compromised. In addition, the Vargel book "Corrosion of Aluminum" specifically states that anodization is not a useful barrier for preventing galvanic corrosion. (ref section 3.11.2)

Good info…….I use brass nipples when building cf rimmed wheels.

Great informative video!! Thank you for this! I always use washers, when the rim bed is flat I use MG washers of stainless steel, in the other case DT Swiss PHR or the Sapim HM. Today I saw the first time of major galvanic nipple corrosion although I use only quality Sapim spoke nipples. I always use lube on the nipple outside also going into contact with the carbon. I always finish with Loctite on the top and bottom of the spoke nipple. I think indeed water can accelerate corrosion. I saw some suggestion to always blow the nipple area dry after cleaning and use oil around the nipple area. Brass nipples can help, but is limited to Black and Silver. Building 1200gram wheels limits the use of Brass. Is there anyone having good results with duralac, lanocote, or tefgel? Which one has the most lubrication effect and is not aggressive to carbon or decals? Thanks for your FB!

Carbon & Aluminum react, I never would have thought that possible.

Very informative! Any evidence showing latex based sealant could accelerate the process? There' a lot of threads saying the amonia is the culprit. There's even latex/amonia free products these days.

The industrial electrical industries use alloy fasteners to connect aluminum conductors to copper conductors especially in grounding grids around skid buildings……something like bronze…

🤔 So… Can I use Nail Polish⁉️💅 Hot Glue? or just stick with Gorilla Tape? The spoke nipples on my ebike wheels are yuge sharp studs that stick out on top of the rim, not embedded in holes, so I want to cover them up properly to prevent another popped tube. The manufacturer used a very thin liner… Can you summarize what materials/substances are safe vs. corrosive to use on aluminum? Thx for saving my tubes/tires/tears/life! 🙏

One thing I noticed was that ammonia can drastically accelerate the reaction. I’ve always had sealant penetration, on every rim given enough time. Wanted to get your opinion on washers for generic carbon hoops. Do they actually reduce the risk of pulling through before reaching a high tension?

What would be more durable through time aluminum-carbon AL-AL or CARBON nipple to carbon rim ? (Counting out Strong hits from trail like Rocks & your own feet)