veganbikes

I was hoping you found a bike belonging to Pablo Escobar...then we could party

This is a case of corrosion caused by sweat. Bar tape is fairly cheap compared to a lot of things. Even some decent tape will only run you about $50 or so and once a year or once every two years depending on your usage of the bike is not so bad. I love when people are like "Ohhh I don't want to replace my nasty tape it is fine" am always curious what lies beneath.

Andrew R Stewart 

First- corrosion will weaken any material it takes to. Second- corrosion will keep trying, like death and taxes. Third- iron oxide (rust) is not the corrosion danger that cyclists generally need to really heed. Al Oxide is.

The weight bearing parts come to mind first. Bars, post, cranks and pedals because of the dangers to control and personal safety. Those that are made of Al are especially to be monitored and serviced periodically. I've seem the bottom of stem quills that have had bits break off (either when in use or when trying to free up a frozen stem). Saddle rails break. There was a while back when Al railed saddles were popular, there's a reason why they are less so these days. Pedal strikes can and have damaged the crank arm eyes or the pedal axles.

I fully understand why so many riders don't follow the best maintenance advise yet are glad to buy and use daily what just a dozen years ago were considered event products. There's a thinking (when those riders really do think about this stuff) that if their not a pro rider, their not putting 10's of thousands of miles a year on their bike, that they're going to get every penny of use they can on that expensive XXX they have and that this mind set is correct. Even the best mindset. After all who doesn't want the pro stuff on their bikes if they can afford it? But corrosion is much more about exposure and maintenance and not power or miles.

Some of what I was speaking to is this lack of accepting that the fancy stuff isn't meant to last longer but more often to weigh less and work nicer (until it's limited life is exceeded). Pros and their sponsors and support people know this. The general public doesn't want to know this Andy

AeroGut

Given that the break is right next to the probably steel(?) clamp, I wonder if the mechanism is galvanic corrosion rather than direct attack of chloride on the aluminum oxide layer? If so this could be prevented by putting a thin layer of tape or some other insulator between the clamp and the bar.

djb

and could overtightening of the clamp or a bike fall have put a small crack there, accelerating the whole process?

Mojo31

Pool chlorine is very corrosive. The fumes are as well. We store it outside and never in the garage.

alcjphil

You know what? I had the very same thought. The reason why is that I owned a 1978 Mercury Zepher, which had cast aluminum bumpers. The bumpers were very thick, at least 1/4". They were real honest to goodness bumpers, I was rear ended once at a stop light hard enough to rattle my fillings but the biggest damage was to the dignity of the twit who hit me, my car was completely undamaged. However, by the time that the car was 5 years old, there were holes in those bumpers right where they bolted to the steel supports of the shock absorbers between the bumpers and the car frame. Other than the holes in those bumpers, they still looked almost new. Montreal uses enough salt on their streets every year to populate a good size city made up of others like the remains of Lot's wife

djb

interesting.
I literally just came up from doing my post ride bike wash in the garage of my alu mtb that I ride most days. Wash it every day when ridden in winter, and a big part of doing that is because of the salt and salty water that ends up all over stuff, so luckily have a garage that I can do a fast, yet pretty good job of getting all the stuff rinsed off. And yes, I sometimes see this white powder in spots that havent gotten rinsed well, like if I take off a wheel, the qr springs and area will have some, so what you are describing goes in with that interface.
Makes me remember I need to do a final wash every so often with the wheels taken off.I do coat these areas with white grease, just to help a bit though., cant hurt.

78 Zepher--dont take this personally, but boy those late 70s to late 80s Mercs and others were pretty ugly....Im a car guy, and I still find a bunch of the late 70s and 80s stuff goofy looking.

cyccommute 

Yes, but most of your other components aren’t exposed to this concentration of salt. Your hands are in direct contact with the bars and there is an absorbent tape that holds the salt sweat in place. You might have a lot of sweat on your saddle as well...I know, TMI...but that probably isn’t going to get on to the metal of the bike. It will likely drip off and get caught in the slipstream that directs it away from the bike. Certainly check your bike and parts but I doubt you’ll see much.

cxwrench

If you really do sweat a ton I'd rinse the bike off w/ water every time it got drenched w/ sweat. Every. Time.

cyccommute 

Not initially. The clamp is in contact with a thick aluminum oxide layer from the anodization which is an insulator. I’m not sure it would be much of an issue even once the corrosion starts. There are certainly ions and water present but the aluminum oxide that is formed will still be electrically neutral. Once enough oxide is eroded, there may be some metal to metal contact but it’s not going to be much contact nor would there be much movement of electrons. I think the cycle of aluminum oxide to Al chloride to Al oxide is relatively rapid and would drive the corrosion more than any electrical potential.

cyccommute 

That’s a different kettle of fish. The aluminum on that bumper probably wasn’t anodized. It’s just cast aluminum with the relatively thin natural oxide layer on it. Galvanic action would be more prevalent in that case. You don’t need much of an insulator to keep galvanic action at bay. A thin layer of grease will do. That’s why you should grease your seatpost and stem. And anodization layer is certainly thick enough to keep electrons from flowing too easily.

Gresp15C

Just an odd question here: Since nobody's going to see under your bar tape anyway, how about painting it? Granted nothing will be impervious forever, but some thick ugly paint might slow the progress of corrosion.

cyccommute 

Might work. Prewrapping with a plastic tape might work as well. A really good electrical tape might work.

oneclick 

If you don't use those new-fangled aero brake levers you will find the brake cable saves your hand from sliding off when you hit the bump.

danallen

Outstanding comment, thank you. You are pointing out an trap easy to be fall into. Specified several high risk points on the the bicycle. Also specified a rule of thumb regarding where the problem is most likely to develop (in the aluminum). You also pointed out that corrosion is not a function of miles or power of the rider. But rather time and environmental conditions.

This is injury-preventing information, possibly life saving. Thank you very very much.

danallen

I think you are onto something:

For starters, I'd say the corrosion appears as you suggested concentrated where the steel clamps contact the handlebars. I did a quick check of steel/iron galvanic corrosion and found this:

Galvanic corrosion (dissimilar-metal corrosion) is an electrochemical process in which one metal corrodes preferentially, when in electrical contact with a different type of metal, and both metals are immersed in an electrolyte such as water.

In virtually any assembly with other common metals, aluminium will be the anode of the resulting cell and hence likely to suffer galvanic corrosion, if the conditions are favourable.

This table provides guidance on using metals when they are I. Contact in the presence of electrolytic water solutions. It recommends against aluminum and steel, indicating high galvanic corrosion is expected, with the aluminum being the metal that will corrode.
​
Source: https://www.sciencedirect.com/topics/materials-science/galvanic-corrosion

It stands to reason, (if my name were Fauci, I would call it "science") that insulating tape between the iron clamp and the aluminum handlebars would block the corrosion, provided it can withstand the forces of being squeezed and pressured when riding on the hoods, especially when braking.

danallen

Answer has to be yes.

danallen

Removed the stem from the handlebars and fork. Both interfaces are AL to AL. No corrosion at all. There are steel to AL interfaces between the steerer tube and cartridge bearings. I was thinking sweat might get into those interfaces, especially the top one, because sweat gets all over the top of the steerer tube and runs down the sides, over the spacers carbon fiber spacers. There was a fair amount of grease on the outsides of those bearing cartridges. That grease might have made the difference. The reason I know sweat gets onto the steerer tube is it gets all over my phone when it is mounted in the middle of the handlebars, right next to the stem/handlebar interface. The sweat come from my head dripping.

sloppy12

shrink wrap it... you can get long rolls of shrink and in different colors to.