Spoke nipples

[SRS]

Hit a speed hump on the way to work the other day.

Three front spokes let go. On inspection, I found that the spokes were intact. The nipple heads had actually rotted away and let go.

These nipples are aluminium in stainless rim ferrules with stainless spokes. I can only conclude that the salt water and sea air in my location is the cause.

I have purchased a cheap wheel to get me going and shall rebuild the original wheel.

Anyone have any ideas as to then best combination of spoke and nipple material?

Bearing in mind that part of my trip to works involves a coastal cycle path with salt water puddles.

Any advice before I commit to buying spokes and nipples would be highly appreciated.

Many thanks SRS

 

[oigoi]

Most good quality wheels use stainless spokes combined with brass nipples. I am surprised and them using aluminium nipples.
Stainless spokes and stainless nipples would be the least likely to corrode though I have had problems with stainless nuts and bolts picking up (seizing) in a wet environment.

 

[johnc461165]

Stainless steel picking up is usually caused by badly formed threads and can be cured by using a Rocol grease to prevent this happening

 

[catsnapper]

Aluminium nipples were developed for weight-conscious roadies, not for coastal dwelling e-wheels
To get the best life from them, spoke lengths have to be optimised to support the entire length of the nipple, but they will usually fail much quicker than a decent conventional nickel plated brass nipple.

Spokes and nipples from leading suppliers such as DT Swiss or Sapim, combined with a good wheel build should give a reliable wheel.
Chinese spokes can be good quality and make a decent wheel as many riders here have discovered - unfortunately plenty have discovered that the opposite can be true, resulting in persistent problems with breaking spokes.

Various lubricants are regularly used on the spoke thread and nipples to assist wheel building. Thread lockers are also used to minimise nipples unwinding under high load conditions.

Alan

 

[bigandy]

What are you have seen is a result of galvanic corrosion. Have a read of it on Wikipedia, and you will see that putting aluminium and uninsulated stainless steel together in a saltwater sets up a galvanic cell, which accelerates corrsions, ultimately leading to failiure. Using grease, or even better, threadlock to keep the salty water out, would help a great deal, but as others have said, using a different material such as brass, would be even better.

Cheers
Andy

 

[bigandy]

Further to my previous comment, this link explains it quite well : Article: Bimetallic (galvanic) corrosion risks from contact with galvanised steel or aluminium

 

[Deleted member 4366]

Whenever you bring different metals together and connect them with an electrolyte (salt water), it makes a battery. The further apart the metals are in the electro-chemical series, the more it behaves as a battery and the faster the corrosion. It's an absolute no-no to bring copper-based metals to aluminium. Even stainless steel and aluminium connected by salt water can cause rapid corrosion of the aluminium without zinc chromate as a corrosion inhibitor.

If you have a stainless spoke in an aluminium motor, there's enough bulk of aluminium that you won't see any corrosion, but a small aluminium nipple in stainless steel will soon rot away.

As long as you stick to normal stainless spokes with the correct size nipple, you won't have a problem.

 

[SRS]

Whenever you bring different metals together and connect them with an electrolyte (salt water), it makes a battery. The further apart the metals are in the electro-chemical series, the more it behaves as a battery and the faster the corrosion. It's an absolute no-no to bring copper-based metals to aluminium. Even stainless steel and aluminium connected by salt water can cause rapid corrosion of the aluminium without zinc chromate as a corrosion inhibitor.

If you have a stainless spoke in an aluminium motor, there's enough bulk of aluminium that you won't see any corrosion, but a small aluminium nipple in stainless steel will soon rot away.

As long as you stick to normal stainless spokes with the correct size nipple, you won't have a problem.

d8veh and others, many thanks for your thoughts and information.

I shall rebuilt this and the original (non motor) rear wheel using stainless spokes and nipples.

I must say that it did shock me when the two spokes gave way, just a small speed hump.

Having now stripped the wheel, I am convinced that a deep pot hole could have caused the entire wheel to collapse with a resultant face plant on the road.