Rusting stainless spokes

Nick Payne

I just noticed, on a front wheel that I built about six or eight years back using Sapim race spokes (swaged 2/1.8/2 stainless steel), a fair amount of surface corrosion on lots of the spokes. See attached images. Interestingly, the spokes on the rear wheel from the same set, built at the same time, also with Sapim race spokes, but of different lengths and so out of different boxes, show no signs of corrosion. After seeing this I examined all the other wheels I have, the majority of them also built with Sapim spokes, and can't find the same corrosion on any other wheels.

I live a considerable distance from the coast - in fact I can't recall that these wheels have ever been near the sea - and the roads around here never get salted, as we don't get enough snow. Other than that these spokes were made from a batch of slightly faulty wire, I can't think or another reason.

veronese68

I believe there are different grades of stainless and different types have different properties. Some are more stainless than others as it were. We sell stainless exhaust systems for cars and they have a lifetime warranty, but they do show signs of surface rust in use. They don't rust through or get heavy corrosion as mild steel does, but they do show signs of corrosion. I vaguely remember once being told that stainless wasn't great for spokes on automotive wire wheels as it was stiffer or more brittle or something, mild steel had more spring so would flex better. These halfarsed recollections make me think it may be that for spokes they use a grade of stainless that is more flexible, but may show signs of corrosion.
That is all conjecture on my part, if you're concerned I would contact the supplier or manufacturer.

ugo.santalucia

I assume Sapim use a Stainless 304.

It's not impenetrable, as the layer of chromium oxide that forms and effectively protects the bulk of the material from oxidation can be corroded in the presence of acid.

I am not saying that you cycled through a puddle of sulphuric acid, but it is possible that if you live in a rather polluted area, nitrogen and sulfur oxides from exhausts mixed with water lead to your spokes being exposed to a higher than normal concentration of acid, resulting in the formation of a superficial layer of rust.

It is interesting that it's the front... the one that is more likely to be in close proximity to a car exhaust.

Wipe it off, it certainly isn't a real world problem... and stop drafting diesel vehicles...

Nick Payne

Actually, I noticed just the other day that Pillar say that they use Sandvik T302 stainless steel for their spokes. The other manufacturers are less forthcoming, though I can remember reading somewhere that DT Swiss and Sapim both use Swedish wire for their spokes.

proto

Nick Payne wrote:

Actually, I noticed just the other day that Pillar say that they use Sandvik T302 stainless steel for their spokes. The other manufacturers are less forthcoming, though I can remember reading somewhere that DT Swiss and Sapim both use Swedish wire for their spokes.

Might mean nothing but Sandvik are a Swedish company.

Alex99

I have a wheel built with Sapim Strong's that is rusting. Very slow though I think so I'll probably wear the rim out first.

cycleclinic

never seen a sapim spoke rust. They use a 18/10 stainless steel. This is as stainless as spokes get. If the sapim is rusting then a DT or pillar would rust under the same conditions. They steel used in all top end end spokes is basically the same grade. it is the grade of steel that determines corrosion resistance.

Alex99

thecycleclinic wrote:

never seen a sapim spoke rust. They use a 18/10 stainless steel. This is as stainless as spokes get. If the sapim is rusting then a DT or pillar would rust under the same conditions. They steel used in all top end end spokes is basically the same grade. it is the grade of steel that determines corrosion resistance.

Maybe I've got that wrong. It's on a shimano nexus 3 hub. Maybe it's rusting in the spoke holes and running down the spoke ends.

davebradswmb

thecycleclinic wrote:

They use a 18/10 stainless steel. This is as stainless as spokes get..

I don't know a lot about the materials that spokes are made of, but 18/10 isn't a particularly corrosion resistant stainless steel - it is fairly equivalent to AISI 304. AISI 316 is significantly more corrosion resistant, but there may be good metallurgical reasons why 304 is a more suitable material for making spokes. However I am sure that if the manufacturers needed a more corrosion resistant material with the right kind of properties for making spokes they would be able to find one. It may simply be that 18/10 is sufficiently corrosion resistant that corrosion will not be a significant issue over the normal lifespan of a wheel.