This post compares the advantages and disadvantages of brass and aluminum spoke nipples.
The Advantages Of Brass Nipples
- Lower Chances Of Galvanic Corrosion
The main advantage of brass is that it’s less anodic than aluminum and thus has lower chances of experiencing galvanic corrosion when it’s in contact with steel.
What is galvanic corrosion?
Galvanic corrosion is a deterioration process occurring when two dissimilar metals are in contact and in the presence of a conductor like water.
When the above conditions are met, a transfer of electrons begins from one of the materials to the other.
In this particular situation, the aluminum or brass nipples are acting as an anode giving up electrons whereas the steel spoke is a cathode receiving electrons.
(Spokes are made of steel because it’s compliant and can bend a high number of times before fully deforming or breaking.)
Galvanic corrosion may keep a nipple almost permanently “welded” to the spoke’s threads.
When a mechanic tries to turn the nipple, there’s a greater chance that the edges of the nipple will be rounded off. Once the nipple is round, it becomes non-adjustable and should be replaced.
In the worst case scenario, the spoke may have to be replaced too if there’s no other way to get the nipple out or the spoke’s threading is damaged too. A similar outcome could turn basic wheel tuning into a lengthy process.
- Easier to Machine
It’s easier to machine brass because it contains lead. Lead is softer than copper and zinc and acts as a lubricant. As a result, there’s less stress on the milling machines and they can operate at a higher rpm. There are also fewer chips.
The same property makes it easier to put threads on brass elements.
The Advantages Of Aluminum Nipples
The main motivation to use aluminum nipples is to save weight. The average aluminum nipples weigh about 0.3 grams which is 1/3 of a brass nipple’s weight.
This results in the following weight savings when all other parameters of the wheel (spoke, rim…etc.) are equal:
|Number of Spokes||Weight Of Aluminum Nipples||Weight Of Brass Nipples||Weight Savings|
The weight savings that aluminum nipples offer go up to 50 grams when the nipples are used on both wheels. 50 grams are not a huge difference and matter only when one wants to own the lightest possible wheels. For recreational purposes, weight savings of this magnitude are inconsequential.
- More colors
Bronze nipples come in three main colors, namely bronze (old-school), silver and black. Meanwhile, aluminum nipples are available in a greater variety of colors. Thus, it’s easier to find a color that suits your wheel better.
In most cases, brass nipples win the comparison because:
- Brass nipples are extremely durable. The rear wheel of my road bike was taken from another unit going back to the 70s. I had to replace some spokes, but the vast majority of the nipples came from the original wheel and are over 50 years old. Their condition isn’t pristine, but they are still usable.
- They experience notably less corrosion and are less likely to bond with the spoke (galvanic corrosion). As a result, one can true the wheel over long periods without experiencing nipple rounding due to applying excessive pressure.
- The weight savings that aluminum nipples provide are not important in the vast majority of cases.
- Brass nipples come in less color, but at the end of the day, the color of your wheel’s nipples is not crucial for the overall aesthetics of your bike.
- If you want aluminum nipples, it’s recommended to go for higher-end models which are naturally more expensive.
Important Tips To Consider
Whether you’re using brass or aluminum nipples, measures should be taken to prevent damage to the nipples when truing a wheel.
The two most important rules are:
- Use the right spoke wrench for your wheels. When the nipples are new and in good condition, you can get away with using a wrench that’s slightly too big, but eventually, the nipples will get rounder. To minimize that chance get a set of quality spoke wrenches.
2. Lubricate the nipples with oil before beginning the wheel truing process. The oil will reduce the friction between the nipples and the spoke threads and make rotations a lot easier.