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Aluminium "rust" on rim


Guest Big H

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We have DRC ST19 40 spoke rims on our Road Tandem. We have not used the bike in quite some time. When the bike arrived in Angola form RSA I thought it might be prudent to clena the wheels. I removed the tyre, tube and rim strips only to discover aluminium "rust" or white aluminium oxide around the eyelets. There is also some oxide visible on the outside of the rim but much less that on the inside.

 

Is this dangerous or detremental.

 

I sprayed some oil on the eyelets and brushed them with a stiff brush. It removed most of the oxice.

 

Should I be worried?????

 

Does this happen due to electrolysis???? I think that is what it is called.

 

20081212_022412_tandem_wheel.jpg 

 

 
Big H2008-12-12 02:30:25
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Yes it is aluminium oxide but it is not dangerous (I don't know if it even tastes nice) or detrimental in THAT location. It is typical of wheels that get wet and stores water through the spoke holes where it slowly evaporates, giving the water lots of time to do its dirty business.

 

Brusihing it off will just get rid of the crystals that have already formed but not prevent any further oxidationl. The only way to prevent that is to keep the wheels dry. If the bike was stored in a bag or other damp place, best to remove and check all alu-on-alu parts such as stem, , seatpost, BB etc. Removing and replacing it now will prevent frozen parts later on.

 

I notice something incidental about that wheel though. The builder miscalculated the length of the spokes and your spokes are now too long. They've bottomed out and thus cannot be tensioned any more. Also, should the nipple round off, you won't be able to get a screwdriver in there to unscrew the nipple.

 

I hope this doesn't cause you sleepless nights.

 

You ask about electrolysis? I dont know if that is a contributing factor. Maybe the chemists here (Homer, your phone is ringing) can tell us if the presense of water where two metals - aluminium and stainless steel or cadmium-plated steel causes any electrolytic activity.

 

 
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Yes it is aluminium oxide but it is not dangerous (I don't know if it even tastes nice) or detrimental in THAT location. It is typical of wheels that get wet and stores water through the spoke holes where it slowly evaporates' date=' giving the water lots of time to do its dirty business.

 

Brusihing it off will just get rid of the crystals that have already formed but not prevent any further oxidationl. The only way to prevent that is to keep the wheels dry. If the bike was stored in a bag or other damp place, best to remove and check all alu-on-alu parts such as stem, , seatpost, BB etc. Removing and replacing it now will prevent frozen parts later on.

 

I notice something incidental about that wheel though. The builder miscalculated the length of the spokes and your spokes are now too long. They've bottomed out and thus cannot be tensioned any more. Also, should the nipple round off, you won't be able to get a screwdriver in there to unscrew the nipple.

 

I hope this doesn't cause you sleepless nights.

 

You ask about electrolysis? I dont know if that is a contributing factor. Maybe the chemists here (Homer, your phone is ringing) can tell us if the presense of water where two metals - aluminium and stainless steel or cadmium-plated steel causes any electrolytic activity.

 

 
[/quote']

 

I remember the footbridge that we did over the N1 at Waterkloof Hoerskool (umlaut op e) was constructed with Corten Steel. It had Aluminium handrails on that has since been stolen and replaced with steel. The original Alimium handraisl had to be bedded on an epxoy to ensure galvanic (?????) or elctrolysis (????) did not take place.

 

The nipples on the rims does still have some play to tighten if neccesary. I will have to play the "tyre lyre", use the JB (Jobst Brandt) or www.sheldombrown.com method this time if I true, tighten or do anything else. I left my trusty Park Spoke Tensioner at home in Pretoria.

 

These wheels were built by an LBS in Pretoria long before I really started getting intersted in wheel dynamics. They have been dogged with breaking spokes since we got them. I seems to have sorted the problem, I hope, just before we left for Mozambique. My interst in wheelbuilding only started when we lived In Mozambique and failing spokes kept on dogging me. The product was a wheel that has since 2005 ARGUS has been running true on the mTB Tandem. (36 hole with DRC 17 rim). I also built a 8 speed 32 spoke wheel that we successfully used on the trainers.

 

I do have a problem though. I purchased twenty spokes as replacement spokes if neccesary. They are all way too long. I stupidly measured the distance from the spoke head to the rim and thought this would work. EK is nou in die tjorts indien ek 'n speek breek.

 

Dankie vir die info.
Big H2008-12-14 03:45:36
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Same question posed on www.bikeforums.net got these replies......

"A layer of aluminum oxide will actually protect the aluminum underneath it from further oxidation. I wouldn't be in the least bit concerned. Let them merrily form their micro-layer of protection and be glad it's there."

and.....

 

"That is actually caused by anodic corrosion due to the dissimilar metals at that joint. You got some moisture in there with a eutectic (salt) and the resultant battery caused the corrosion. Unless the there's major damage to the holes, you should be fine."
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Cut cut cut cut....

 

The nipples on the rims does still have some play to tighten if neccesary. I will have to play the "tyre lyre"' date=' use the JB (Jobst Brandt) or www.sheldombrown.com method this time if I true, tighten or do anything else. I left my trusty Park Spoke Tensioner at home in Pretoria.

 
[/quote']

Luckily you won't need it. Unless you have data that takes into account the number of spokes, the type and diameter of spokes, the specific rim and hub detail and, the collapse tension for that combination in order to

There are other more accurate ways of arriving at the optimum tension.

 

 

But then again, you know that I know that you know that.
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