Steel Crown Race on Alu Steerer

[AnnaStravard]

Just wondered is a steel fork crown race ok on an alu steerer? Just wondered if galvanic corrosion would be an issue?

[rogerzilla]

The race wouldn't be much good if it were made of anything but steel.

It's fine - I won't personally ride a bike with an alu steerer, but that's another matter.

[pwa]

Just get a good smear of copper slip in there.

[DaveP]

I hope that was meant to be tongue in cheek - it''s really not a good idea to put copper in contact with aluminium in any location that can get damp!
The copper will cause corrosion in the ally. Use Aluslip, or failing that, plain grease.

[AnnaStravard]

Thanks guys I’m trying to get some knowledge to impress my husband as he’s always going on about stainless steel aluminium etc this will be my first headset install...under supervision.

[Si]

I hope that was meant to be tongue in cheek - it''s really not a good idea to put copper in contact with aluminium in any location that can get damp!
The copper will cause corrosion in the ally. Use Aluslip, or failing that, plain grease.

That's something that I'd not heard before. Indeed, I've been instructed by numerous sources over numerous years that one should put copperslip between square taper BB axles and Alu cranks. Well, you live and learn.

[Jdsk]

I hope that was meant to be tongue in cheek - it''s really not a good idea to put copper in contact with aluminium in any location that can get damp!
The copper will cause corrosion in the ally. Use Aluslip, or failing that, plain grease.

That's something that I'd not heard before. Indeed, I've been instructed by numerous sources over numerous years that one should put copperslip between square taper BB axles and Alu cranks. Well, you live and learn.

Does this cause problems in practice?

Here's a "copper anti-seize lubricant" that's specifically recommended for "Spark plug threads installed in aluminum".
https://www.permatex.com/products/lubricants/specialty-lubricants-anti-seize/permatex-copper-anti-seize-lubricant/

Jonathan

[Brucey]

I hope that was meant to be tongue in cheek - it''s really not a good idea to put copper in contact with aluminium in any location that can get damp!
The copper will cause corrosion in the ally. Use Aluslip, or failing that, plain grease.

That's something that I'd not heard before. Indeed, I've been instructed by numerous sources over numerous years that one should put copperslip between square taper BB axles and Alu cranks. Well, you live and learn.

never use such products on square taper cranks; the fit depends on partial seizure and anti-seize compounds will inhibit such processes.

Good information about compatibility of anti-seize materials is hard to come by. Much of it is simply bogus or only mandated by the manufacturers of specific (and expensive) products, under highly specific conditions (eg high temperatures). FWIW Rocol make a copper-based anti-seize to Royal Navy specifications, and those specifications do not mention any restriction about materials combinations; IIRC it says 'all metals'. 'Dampness' is almost guaranteed.

There is a galvanic cell present between steel and aluminium anyway; using aluslip might make some sense between two pieces of aluminium, rather less so between steel and aluminium. To further complicate matters copper anti-seize compounds vary (in copper content between about 2% and 50%) and most contain other anti-seize ingredients which also have their own galvanic potential.

In any event an oil or grease-based compound will help to exclude water for a while, and without water there will be no corrosion. Wax-based compounds will also exclude moisture and inhibit corrosion too.

IME it doesn't matter what you use if the parts are then subject to road salt; corrosion is almost inevitable.

cheers

[pwa]

I hope that was meant to be tongue in cheek - it''s really not a good idea to put copper in contact with aluminium in any location that can get damp!
The copper will cause corrosion in the ally. Use Aluslip, or failing that, plain grease.

What I use, to be precise, is Finish Line Anti-Seize, which is copper coloured and I had assumed (wrongly?) to be a variety of copper slip. I have used it on ally seatposts in steel seat tubes. Is that wrong? I also use it on steel pedal axles in ally cranks. And on stainless steel bolts in ally frames.

My Anti-Seize is in a tin and is still going strong after more years than I care to remember, but SJS have these stupid little sachets:

https://www.sjscycles.co.uk/lubricants/ ... c-sachets/

which the blurb claims to be suitable for all sorts of materials (inc ally and steel) and moist conditions. "Use on all threads and press-fit parts" it says on my own 8oz tin. Without further investigation I don't know if it contains copper, but it does have that colour... The tin is not forthcoming about ingredients.

For some reason I had always taken it to be "copper slip" grease and have been careful to clean hands after use because it seems likely to contain things best not ingested.

[DaveP]

I had a vague memory of this being a subject of discussion some years ago, so I did a quick "google". I just typed "copper and aluminium" and "electrogalvanic corrosion* popped right up. I knew my memory wasn't that far gone! The actual scientific basis is both clear and established. Does it make any difference in practice?
If you slather it all over your cranks the worst that is likely to happen is that you might end up chucking them after a battle to get them off.
With an aluminium steerer - How lucky do you feel?



Almost totally irrelevant but an impressive demonstration of metal on metal action: https://www.youtube.com/watch?v=IrdYueB9pY4

[Brucey]

copper ease (or other anti-seize) is just the job for pedal threads but as I said before under no circumstances should you use it on square tapers. Especially not if you push hard on the pedals.

In order for the ST interface to work the crank becomes partially seized on the BB spindle; that this happens should be evident from the difference between the tightening torque of the bolt and the loosening torque when using a crank extractor. If seizure doesn't occur then the crank to BB spindle interface has a much-reduced torque bearing capacity.

What can happen with anti-seize present is that the crank just continues moving around on the taper for ever, with predictable consequences.

IME with a small amount of 'normal' grease (i.e. without solid lubricants and anti-seize/EP additives, so oil plus thickener only) this allows the joint to 'settle' or 'size' itself (which allows for discrepancies in machining) during installation and then a small amount of movement may also occur in initial service. If the movement is persistent it generates fresh aluminium surfaces which (because aluminium is highly reactive; it will rob oxygen from pretty much anything else) will then react with the grease, turning it into something that is more like a glue than a lubricant. Excess grease will get squeezed out of the joint (slowly, over days potentially) anyway. The result is that such joints tend to settle; commonly the bolt torque required to remove the bolt goes down whether you ride the bike or not. If there is much movement in the joint initially the bolt will often loosen enough that it is desirable to retighten it after a hundred miles or so.

cheers

[gregoryoftours]

The race wouldn't be much good if it were made of anything but steel.

It's fine - I won't personally ride a bike with an alu steerer, but that's another matter.

Lots of cartridge bearing headsets have aluminium crown races. Obviously not caged bearing headsets though.

[pwa]

The race wouldn't be much good if it were made of anything but steel.

It's fine - I won't personally ride a bike with an alu steerer, but that's another matter.

Lots of cartridge bearing headsets have aluminium crown races. Obviously not caged bearing headsets though.

I think those "races" are races only in name. The actual "race" is within the cartridge.

[gregoryoftours]

The race wouldn't be much good if it were made of anything but steel.

It's fine - I won't personally ride a bike with an alu steerer, but that's another matter.

Lots of cartridge bearing headsets have aluminium crown races. Obviously not caged bearing headsets though.

I think those "races" are races only in name. The actual "race" is within the cartridge.

Yes technically that is true.

[squeaker]

Almost totally irrelevant but an impressive demonstration of metal on metal action: https://www.youtube.com/watch?v=IrdYueB9pY4

Nice