[Uprwstsdr]

My DA cranks look like they have flesh eating disease. They have small blothches all over them. I had been riding a trainer over the winter and thought it was possibly dried salt form sweat. I have tried to clean it off, but not much luck. I had the bike with me at the LBS ysterday and they said the aluminum was corroding. Apparently, the finish eventually wears off and the the metal starts to corrode from exposure. Is this true? Is there anything I can do to stop it or do I am looking at eventual failure here? The cranks are 10 years old.

 

[wim]

Your diagnosis is correct. Corrosive sweat droplets left on your cranks ate through the anodizing layer and attacked the bare aluminum alloy. While surface imperfections often start cracks, I can't see certain failure of your cranks because of that alone. But the age of your cranks, and my assumption that they've not been inspected and maintained as much they should have, would make me consider replacement.

The only way I know to make them look better is to remove all the anodizing and then polish the bare aluminum alloy. However, stripping the anodizing off is a huge chore. Also, bare aluminum oxidizes easily, so you'd be in for regular crank polishing sessions. Not something I'd want to do.

 

[skepticman]

You could try some aluminum polish like Blue Magic (available in auto parts stores). I use it to polish aluminum car wheels that don't have a clear coat. It's amazing stuff that will turn gray oxidized aluminum into a mirror-like finish. It claims to leave a silicone layer on the metal to prevent further oxidation, but it only works so-so.

I use a protectant called RejeX from Corrosion Technologies after polishing with the the Blue Magic and that does keep the shine longer, but RejeX is expensive and probably not available locally, just online.

 

[rePhil]

What do you clean them with?

Simple Green will attack the finish. Living & sweating in Florida I know a bit about toxic sweat. I wipe down after every ride, clean with mineral spirits and use Bike Lust or Pledge often. I had a pair of Ebay cranks that looked horrible. I ended up keeping them clean but not worrying how they looked. There was no way I was going to polish and maintain the raw aluminum

 

[SPINDAWG]

My 7700 Dura Ace cranks had this happen as well.

Shows up only on the inside of the crank though. They have had this problem for years,without any signs of more of these blotches happening,as I make sure to wipe them down from time to time.Doesn't seem to effect the performance of the crank however,so I'm not worried about any possible failures in the imediate future and if it does I'll have more of a reason to convert my last bike over to Campag even though I have mutiple Dura Ace cranks on hand.

 

[Uprwstsdr]

Thanks for the responses

I thought I was wiping them down enough, obviously not. The other day, as I thought it was just salt I cleaned them with hot water, soap and a toothbrush. This didn't accomplish much (no suprise there). I will try the Blue Magic and just be diligent about it. The corrosion is not severe, so I don't anticipate failure anytime soon. Although, the guy at the LBS did point out the new Stronglight Pulsion cranks that had just come in. These bad boys are sweet. I just might be better off playing it safe, you never do now what could happen.