Henry III

I'm curious on when hard anodized rims first appeared on the scene? I'm trying to keep my late 70's Guerciotti period correct but received a NOS of unknown grey anodized tubular rims and my current rims on the bike seriously need to be recycled.

kroozer 

Mid-70's.

Chombi

Dark anodized rims stated coming up in the late 70's on high line bikes and pretty much became the rage during the 80's....so your late 70's Guerciotti should be OK with the grey anodized rims. But frankly, I think your bike would look correct with either clear silver anodized rims or dark anodized one as it's in that transitional period anyway. I wouldn't use dark anodized rims on most early 70's bikes though.... JMOs

DIMcyclist

Was there any actual difference in how well the darker or lighter anodizing of the time lasted, or was the darker grey purely an aesthetic/ design-related choice? Or was it a technical decision, based on performance or arcane UCI rulings or something?

I've always been just a bit curious about that, as about the only color I've ever seen on rims of the time is basic battleship-grey. I've always wondered if that was due to some kind of racing regulation-thing.

Chombi

I've also wondered what "hard" anodizing meant as they used it mostly to describe a lot of the darker anodized rims that were sold in the 80's. Is it really a "harder" type of anodizing. I was also wondering why the rim manufacturers seemed to have hinted that "hard anodized" rims were somewhat stronger than "regular" anodized rims. For a coating that's literally just microns thick, I could not see any big structural strength difference between the two, unless some sort of heat treatment accompanied the hard anodizing process?? One thing I did notice is, My old Fiamme Ergals are much softer/noodlier than my similar weight and width Mavic GEL280s. I suspect heat treatment is what is in play and not the dark anodizing on the Mavics....

zukahn1 

Hard anodizing appeared first in the 60' showed up on high some bike parts in late 60's early 70's. For period correctness basic early har annodized rim should be fine on a late 70's bike.

repechage

Well, that post went vapor. I think if you guys really reference, "dark anodized" rims came late late 70's early 80's.
Colors came in the mid 70's Nisi Oro range first.
Hard anodizing is just the "added depth" to the effected material.
I think they came with the revisions to the alloy used and that gave the added strength.

Fiamme was late to the party, their alloy was softest for so long. But they polished up so well as a result.

The Mavic SSC's in the original dark blue grey were the rim that in the pro peloton really brought the avalanche to anodized rims.

zukahn1 

Good point hard annodizing had nothing to with strength and quality it was a finishing proccess too put a colour finish on alloy product.

gaucho777 

It is more than simply a finishing process. Anodizing, or hard anodizing, makes the surface both more corrosion resistant and more resistant to wear. The drawback is that the wear from the brake pads leaves some ugly streaks over time, but along the way the brake pads won't thin the rim walls as quickly. At least that's my story and I'm sticking to it. Something I don't see mentioned about hard anodized rims is that hard anodized surface do not conduct heat very well. I don't have any data to compare heat transfer of anodized vs. non-anodized rims, but his would seem at least in theory (or marketing angle), to promote braking performance and reduce the risk of overheating a tubular rim.

I'm not sure what was lost in repechage's vaporized post, but this little nugget about Martano rims stuck in my head.

If I ever come across a good deal on some Martano rims...

Grand Bois

Anodized vs. Non-anodized Rims by Jobst Brandt

gaucho777 

^Thanks for the link. Apparently I erred in my supposition that reduced heat transfer in the rims would increase braking performance. Rather, the pads carry more heat. So says Jobst.

unworthy1

funny how Jobst talks at length about all the negative structural affects of anodizing (both regular "cosmetic" a well as "hard") and then concludes with "Anodizing is not heat treatment and has no effect on the structural properties of the aluminum. "
He's got a lot of it correct, anodizing creates a layer of (harder) aluminum oxide on/in the outer surface of aluminum, this same Al2O3 will occur naturally from plain exposure of raw Al to air, but anodizing artificially makes it thicker.
"Hard" anodizing is merely taking the process farther along so that the oxide layer is thicker still so more of the "harder" oxide replaces the softer Al...Jobst points out that this is a trade-off that gives you a thicker harder coating but that's not necessarily a stronger rim!
Color is merely the dye that's added to the liquid bath in the electro-chemical anodizing process, it could have been anything (purple, teal, pink) but maybe dark gray was a fashion call or just looks better in that thicker layer of oxide.

Grand Bois

He says that anodizing does not strengthen the rim, and thicker hard anodizing tends to crack and the cracks tend to propagate into the metal. That makes sense to me.

noglider 

Does anyone know about Jobst's health these days? There's not a lot of of news, and the last bit I read wasn't all that good.

Grand Bois

From sheldonbrown.com:

"Brandt suffered a broken leg in what appears to have been a single-bicycle crash (no witness reports) in January, 2011. He also suffered brain injury. According to one report, this was from a stroke while he was in the hospital, rather than the crash itself -- though he famously did not wear a helmet. He has not posted messages since."

I also read on rec.bikes that he has recovered and is in good spirits.