Keep an eye on them for signs of galvanic corrosion.

I have a set of DT Swiss RC28 C DB wheels on my bike. I had a spoke come loose the other day, the problem is the have internal, inverted nipples, so the only way to check them is by removing the tyre and rim tape, and this fell out.

I contacted hotlines, but they don’t do warranty, that is TFTuned, so I contacted them. All they could do is offer to look at them, and replace with the same, alu nipples. After some discussion, they mentioned that Sapim did brass inverted nipples. I ordered some from eBay and spent the evening replacing the rear wheel nipples.
This is was came out, including 3 twisted spokes, with one snapping where I could not release the nipple. The tensions were also all over the place, with a couple of spokes down at 5 on my park meter.

The front looks okay, but I’m going to replace them with brass anyway.

similar to ENVE, used to be Pillar Aluminium, now propietry Sapim brass nipple (2 quid each at JRA !!!) however free if you bought retail and ask, as the warranty now requires the use of them

my road ones looks like this after a year, my MTB ones were similar, if not worse, some crumbled, not a chance of getting the spoke out of them

I’m a bit peeved that DT don’t offer a brass option.

Aluminium is a silly choice for nipples really for carbon, they are bad enough with an alloy rim. You need titanium ones as stainless would be no good due to galling with the spoke thread.

That’s pretty bad. I actually built my original lightbicycle with alu nipples, dt prolocks, and after 2 years they’ve got barely a mark- maybe the anodising protects them more? But it was a worry.

What is it in the carbon that reacts with the aluminium? Anyone know?

Aluminium and stainless steel (spokes) is a really bad combination for galvanic corrosion.

Ali nipples regardless of what the rim material is, is a bad idea.

That is weird. I built my LB rims with black alu nips and they were fine after a year or so. Well they kept breaking because I used spokes that were much too short, but no corrosion when I rebuilt them!

Found this interesting article :

Corrosion

What is it in the carbon that reacts with the aluminium? Anyone know?

The carbon.

Well, strictly it’s the oxygen in the air, but when you put two dissimilar metals in an electrolyte solution (water, particularly if it’s salty) then you create an galvanic cell (aka a battery). As carbon has a similar structure, conducts electricity and undergoes oxidation similar to metals it can act in the same way.

Best example is a ship or oil rig, covered in steel and aluminium components, so they put a big lump of zinc in the water attached by a cable. This forces enough voltage the other way that the zinc oxidizes rather than the other metals. Hence why steel objects are galvanized, it provides a layer of zinc that even if scratched or worn away will protect the exposed bits. Another common one is a blast furnace, in that case the solution is molten iron, the carbon is the coke which strips the oxygen off the iron ore.

For common metals the order is

Zinc
Aluminium
Carbon
Steel

Stick 2 or more together and the most reactive will corrode first.

andyl – Member
You need titanium ones as stainless would be no good due to galling with the spoke thread.

Surely Ti would be worse for galling than SS?

DT can’t win really, if they used Brass everyone would suck through their teeth because the wheels would be about 100 grams heavier and now ‘X’ brand’s wheels are lighter blah blah blah.

DT offer all their nipples in brass except for the ‘hidden’ ones for carbon aero wheels. I guess they think that if you’re going splashing out on carbon road racing wheels rotating weight will be your primary concern. In fact I can’t think of a off the peg carbon road wheelset that uses brass nipples.

Most severe alloy nipple corrosion I’ve seen has been as a result of winter use with road salt, not the natural habitat for carbon race wheels such as the RC28’s.

I had a carbon seatpost, carbon frame and an alu shim. The carbon frame was raw on the inside, and this resulted in a load of alu oxide on the outside of the shim, where it contacted the frame.

I could do with a carbon shim..!

I could do with a carbon shim..!

Most plastic shims should work?

Well, I ride my bike all year, and all weathers, that is why I got a disc brake bike. There is not much salt use on the isle of man, and I’m not usually out in icy conditions.

Eh? What’s the relevance of the brake type?

As above, if you have alu nipples they will basically make a cell with the spoke itself and possibly the rim. The spoke forms the anode, so will waste away and leave corrosion product which will cause it to seize in place.

For race wheels though I would probably stick with alu nipples for the weight saving, and no racer is going to want 100g more rotating mass just for ease of truing down the line.

There is not much salt use on the isle of man

Luckily you are always a long way from the coast and all that nasty salty sea.

[Quote]. Surely Ti would be worse for galling than SS? [/quote]

Titanium nipple with a titanium spoke of the same grade would be at risk of galling. Stainless spoke with titanium nipple less so. Or an different grade of stainless for the nipple and use some line and turn slowly, especially as the tension builds.

Where can you get titanium nipples?

no racer is going to want 100g more rotating mass just for ease of truing down the line.

22g vs. 64g for a pair of 32h wheels. 42 grams is not that much here.

Carbon rims, alu nipples. Keep an eye on them for signs of galvanic corrosion.

Yeh my carbon rims / alu nipples show a similar problem.

Hmm OK my 100g was from someone’s post earlier on – 42g is about the same difference as replacing one mid range alu rim with a top end alu rim on a road bike though, and it’s a massive percentage (and all these small things add up once you have an entire bike).

In terms of what corrodes from any dissimilar metals in contact, look at the table towards the bottom of this:
https://en.wikipedia.org/wiki/Galvanic_corrosion#Galvanic_series

I’m not sure where carbon would sit in the table, I assume more cathodic than aluminium. Anodising will help, but I’m not sure how much.

Had same corrosion on my LB wheels. A couple of spokes snapped out of the blue but when i went to change these i noticed both my wheels showed same corrosion. Seems quite common but probably depends where you live or ride as to how long it takes to be evident. Spokes snapped after 14 months, the rest were seized solid. In the end i replaced the spokes – Pillars to DT Comps and nipples – alu alloy to brass. I wouldn’t order alu alloy nipples again. Had to cut the spokes to get them out of the wheel. Brass nippled wheels have been fine and and show no signs of similar corrosion. Can’t say i noticed the extra rotating mass!!
Grinder

I’m not sure where carbon would sit in the table, I assume more cathodic than aluminium. Anodising will help, but I’m not sure how much.

Between steel and aluminium, hence we managed to get metal from rocks by chucking them on the fire with some coal for 1000’s of years, but it took reliable electricity in the last 100 to get aluminium.

Ah, right you are TINAS. Makes sense.

Decent anodized nipples should be enough for several years use even on carbon, with a bit of Ti prep for good measure they should last as long as the spokes. (3 year old lightbike rims, CXrays and anodized nipples)

Well, now I’m gettin even more peeved with DTSwiss. I managed to find 3 dt bladed spokes at my lbs in their box of spares. I get home and they don’t fit through the holes in the straight pull hub. Measuring them with the spoke measuring tool that came with my park tension meter, the spokes on the bike fit through the 2.16mm hole, but the new ones are just wider. Checking dt website, all their bladed spokes are 2.3 wide. So, proprietary spokes and hubs, and nowhere to get them.
👿

DT do about 3 differnt kinds of aerospoke, some are wider and deeper than others.

TF Tuned are the U.K. service centre for the wheels and will have service packs of spokes.

I phoned them today. They don’t usually sell spokes, as they have stock for service and warranty only.

They did offer to see if they could help. I’m just waiting for a response.