By Joss DeWaele — As a mechanic, when a customer comes in with a set of carbon bike wheels with seized spoke nipples, this presents a problem.
Due to an excessive build up of what is likely aluminum oxide, your customer’s aluminum alloy spoke nipples will no longer turn on the spoke threads, making it impossible to adjust the tension on the spokes. But there are feelings to consider, and you’re about to hurt some of them.
If the spokes are in relatively even tension, and if the tension on the spokes is still reasonably high, your customer can likely ride the wheel for a bit longer. How much longer is tough to tell. Nipples with heavy corrosion have a tendency to fail, especially when under tension.
If the rim has a noticeable wobble of hop, or if the spoke tension varies widely, your customer’s only choice is to rebuild the wheel—preferably with new spokes.
“But I just bought those wheels last year,” your customer says. “I paid a lot of money for those wheels.”
She (or he) is right. They did. “Surely this is a defective product,” they say. “Isn’t this covered under warranty?”
Perhaps. It’s always worth checking with the manufacturer.
From a wheel builder’s perspective, every wheel should be built with brass nipples.
From a product development perspective, one must consider that the first number anyone will look at when considering a purchase of a new, pre-built wheel set is that wheel set’s overall weight. Using brass nipples can change that overall weight by 30-90 grams of rotating mass. While that 30-90 grams might not seem like a lot of weight, it is a significant amount of weight when one is tasked with building a wheel for competition at the highest level, which is also what most people are looking for when considering a purchase. What are the top athletes running?
So let’s use the automobile analogy because we’re in America and everyone can relate. In comparison with cars, any bicycle with carbon wheels is an extremely high performance machine. Let’s call it a Ferrari, because that’s fun.
When you buy a Ferrari, there’s a certain understanding that more regular maintenance comes along with owning a high performance machine, leading to higher maintenance costs during ownership. No one ever says, “I paid two hundred thousand dollars for that car, how come I have to replace the tires already.”
Strangely, with bikes, there is often an assumption that higher costs will bring less maintenance. In reality, racing bikes with racing components are designed under a competing assumption, which is that the machine will receive regular cleaning and fine tuning.
The cause of aluminum alloy nipple corrosion is beyond the scope of this article, but a video digestion by Bill Mould of a University of Denver Doctoral Thesis titled, “Galvanic Corrosion of Aluminum/Carbon Composite Systems” can be found on YouTube by searching for Bill Mould and aluminum nipple corrosion. Caution: it’s boring. Bill Mould is a wheel builder, and from his perspective, every wheel should either be built with brass nipples, or a washer between the nipple and rim.
So for everyone out there riding a set of carbon composite rimmed bicycle racing wheels, here is a short list of suggestions on how to best care for your wheels and protect your investment. The suggestions below also apply to any other bicycle wheels, regardless of cost.
- Check spoke tension with every new set of tires. The strength of the wire wheel is dependent on the uniformity of tension on the spokes.
- When you ride in wet conditions, apply the smallest amount of chain lube possible each spoke nipple. Caution: don’t get lube on your brake track.
- Clean the brake track regularly with isopropyl alcohol. You don’t have to go nuts with this; clean the brake track every time you clean and lube the drivetrain.
- A clean bike is a happy bike. Going back to the automobile analogy, you wouldn’t drive a dirty Ferrari, right?
To quote timeless wisdom, an ounce of prevention is worth a pound of cure.
Joss DeWaele managed bike shops for ten years before slinging ink for a short stint with Decline and Road magazines. He currently works for Reynolds Cycling in Sandy, Utah.