elfmachine

Hello. I installed a SunRace CNM84 chain on my bicycle last year and after many months it rusted so much that it got stiff. Pretty strange that it rusted so strongly despite being plated with chrome or nickel. I didn't have time to lubricate it so I rode my bike with an unlubricated chain which became more flexible after a ride. Now removed the chan and placed it into a bath with phosphoric acid with zinc aka rust remover to remove rust before lubricating it with teflon wax. After a while I started hearing popping sounds and after chain inspection I noticed that many links had cracks! Did rust remover somehow cause breakage or cracks developed from riding an unlubricated rusted chain?

Iride01 

Might be hydrogen embrittlement. I wouldn't use anything but lube to free up a rusty chain. It's worked for many that were rusted solid.

Mr. 66

I don’t think that’s a good product to use, vinegar or wood bleach would have been a safer use. A light wire brush would have been fine. If you had just put lube on your chain would probably be ok, perhaps worn.

cyccommute 

Phosphoric acid is a surface rust remover and should not be used in any kind of bath. The iron in the chain will react with the phosphate which is what lead to your cracking. I suspect that the chain also cracked near the name embossing on the chain plates. The embossing introduces some micro fractures that the phosphoric acid can utilize to get into the metal. That can lead to widening of the cracks and the ultimate failure of the chain. It will look similar to the cracking caused by salt in the picture from this post




Although I would replace any chain that is has rusted stiff enough to not move any more, if you absolutely have to remove rust, use Evapo-Rust which is a chelating agent that doesn’t attack the iron in the chain. It’s far less hazardous than phosphoric acid and won’t damage parts.

cyccommute 

A chain that is “rusted so much that it got stiff” has rust inside the plates that would have to be removed. That negates the use of a wire brush to remove surface rust which is mostly cosmetic. Naval Jelly (phosphoric acid) or acetic acid (vinegar) or wood bleach (sodium hydroxide/hydrogen peroxide or oxalic acid/chlorine bleach) are all very harsh chemical treatments that will likely lead to dissolution of the steel and, ultimately, cracking. The best course of action would be to just replace the chain.

However, if the chain is The Precious and just has to be kept, Evapo-Rust would be a less destructive removal method.

bblair

You spent a lot of time working on a chain that you didn't have time to lubricate.

I think that your chain broke from simple rust and corrosion.

elfmachine

That's exactly what happened to my chain Can you explain how acid was able to break chain links, zinc coating build up in crevices? This was bad chain to purchase, should I avoid embossed chains? It was more expensive chain so I hoped it would last longer but I was wrong.

FBinNY 

While the chemistry may have sped up the chain's failure as noted by others, you have to keep in mind that the rust itself already compromised it.

Chain plates are thin, so any significant rust means a decent percentage of the plates' cross section is weakened. Concern over weight, and the physical space constraints ensure that chain plates don't have much excess plate material to spare.

Light cosmetic rust is fine and can be ignored but serious deep rust is death. Concern about rust should be focused on prevention, not removal, and certainly not removal chemically.

elfmachine

Yes, it was exposed to salt used to melt snow. But I heard popping sounds when I filled the chain with rust remover. I want to know what exactly damaged the chain so as not to repeat mistakes again.

cyccommute 

All chains are embossed. It’s how companies mark their chains so that you know what chain you have. Most of the time, that embossing isn’t a problem and doesn’t have any effect on the strength of the chain. But the chain wasn’t meant to be soaked in reactive chemicals, either. Salt on the surface isn’t much of a problem, especially if it is rinsed off occasionally. The chain in that picture had to be soaked for weeks in a salt solution as part of a demonstration of what happens when a chain is soaked in a water based “mineral spirits” solution. You can read the gory details here.

Naval jelly works to take surface rust off of steel exposed to weather but it is meant as a surface treatment. The phosphoric acid reacts with the iron to make iron phosphate which is water insoluble and prevent further rusting but it isn’t meant to be used as a long term soak. It should be allowed to react for perhaps hours but not for more than that. And it is usually used on something that is not load bearing. You might have built up a zinc coating on the surface but the phosphoric acid was eating away at small cracks, making them into larger cracks.

If you really need to soak something to get rid of rust, the Evapo-rust solution works better and really is meant to soak for hours to days.

cyccommute 

While I agree that the chain should be replaced if it is that rusted, I don’t think that a rusted chain is necessarily severely weakened. Replacement is warranted because removal of the rust is often going to be more expensive and time consuming than just replacing the chain.

The rust does indeed consume metal to make the oxide but the amount of iron consumed to make a lot of iron oxide is relatively small. Iron oxide has a volume that is 6 times that of the iron. That would mean that a block of iron 1mm cubed would result in a block of rust 6mm cubed. There isn’t much room inside of the chain plates so even a little bit of rust would bind the mechanism.

elfmachine

I soaked it only for 10-15 minutes and during this time I heard popping sounds. It is hard to believe that rust remover had enough force to actualy break steel. Could this be chain quality issue, it being fake substandard?

grumpus

Using a chain in salty conditions, you need to regularly wash off the salt, displace/dry remaining moisture and add lubricant. If that's too much effort, at least keep it well lubricated, it doesn't take long to drip on some oil. Good fenders can help keep salt and grit off the chain. Chains are consumable items, as soon as they get stiff and rusty it's time to replace them, and treat the new one better than the old one: then you might wear it out instead of letting it rot.

cyccommute 

The salt isn’t going to do your chain any favors. The caustic rust remover just exacerbated the problem and probably enhanced any cracking that the salt started.

Road “salt” can be various different materials that chemists call salts. All of the “salts” used on roads are going to be chloride based but any substance formed from a Bronstead-Lowry acid/base reaction is a “salt”. For the chloride salts commonly used, all of them are hygroscopic or “water absorbing” but some are more hygroscopic than others. The hygroscopic mechanism literally sucks water out of the air and makes the salt wet. “Mag chloride” does a much better job of sucking water out the air than sodium chloride.

If the salt were dry, it would do nothing to the metal. But add in just a little bit of water and the salt and metal start to dance like it’s Prom night! The chloride in the salts pluck iron atoms out of the metal and then exchanges the chloride for oxygen which releases the chloride to go back and get a new partner. This keeps up until all the iron have been married to oxygen or until the system dries out…which is almost never.

Phosphoric acid doesn’t do the same kind of dance but it is quicker at reaction with the iron to make iron phosphate…kind of like a rave vs Prom night. The reason it is used to remove “rust” is because the phosphate iron will take the place of the oxygen in the iron oxide compound. It also reacts with the unoxidized iron quite readily leading to removal of that iron. Micro cracks caused by the embossing just offer an area where there is more surface area than on the flat of the metal.

Lubricants, by the way, do serve a propose to keep the salt out of the chain and to keep most moisture out. They are party poopers

elfmachine

I stopped lubricating chain with oil and now I use cleaner method of dipping chain in microcrystallne wax with teflon powder. But before doing that I clean away grit with water and used rust remover to remove excess rust. Are there chains made of more corrosion resistant alloys?

FBinNY 

The rust remover didn't break the steel.

What you didn't consider is that each outer plate is force fit over the pin. That means that there's considerable radial stress at every pin. What happened is that the now weakened plates cracked under that stress.

Andrew R Stewart 

It is interesting to read a thread and see the repeated, confirmed, missing at first and added later details go through their "dance".

I think this thread just shows one of the lacking aspects of a wax chain lube... The ability to "recoat" the chain's surface where it has rubbed against itself, sprocket teeth and der cages is a big reason why wet lubes are better in wet conditions. Andy (who has lived in the Rust Belt most of his life)

grumpus

There are titanium chains, but just frequent rinsing with water will remove most of the salt from a waxed chain and slow the corrosion.

FBinNY 

I stand by my original statement, which included the qualifier "significant".

Badly rusted chains are most definitely compromised. The OP's didn't fail under load, it failed from pin stress.

Given the potential consequences of chain failure under load, which run from inconvenience to serious injury, trying to save such chain doesn't make sense, even if time weren't a factor.

elfmachine

Titanium is great material but it rare and expensive. So I will have to stick to the steel chain.

cyccommute 

It would be hard to say where the popping sounds came from. Going way out on the speculating limb here, but the presence of chloride could change the chemistry. You might have formed zinc chloride which is highly acidic and, in the presence of the phosphoric acid, could increase the rate of reaction of the mixture with the iron. If the metal was already stressed by the chloride, the faster reaction with the zinc chloride/phosphoric acid mixture may have been enough to cause the metal to crack more quickly.

SunRace products are cheap. They may not be using the best steel around for their chains. Shimming a bit further out on the speculating limb, there may have some aluminum in the Slagesium that is used for very cheap bicycle products. Aluminum doesn’t alloy with iron so you may have been hearing reactions of the aluminum with the phosphoric acid mixture which can form hydrogen gas. That, however, is very wild speculation. I may have fallen off the limb entirely.

I have used some of their cassettes and they are pretty good products. I don’t know that I would use one of their chains, however. I don’t spend a lot of money on chains but using a SunRace one is probably too cheap for me.

At this point it would probably be difficult to replicate your observations. You can learn from this exercise with the biggest take away being “don’t do that!” Other lessons would be lubricate your chain, rinse it often, and, if it gets stiff with rust, just replace it.

FBinNY 

Despite an obvious bias, I'd hate to see this derailed to a chain lube thread.

Chains have a relatively short service life, so it's not necessary to totally prevent rust. It's only necessary to slow it enough that the chain wears out before rust is a problem.

This is easy enough for those who actually ride their bikes, regardless of their choice of lubes.

veganbikes

Lubing a chain takes about 1 minute pedal backwards drip some lube on to the chain and then continue pedaling backwards with a rag and wipe the excess. That is simple and easy and will get you done and at least prevent rusting. Sure you could spend more time and clean and lube but you claim to not have any time which is guaranteed not to be true in any form or fashion, so the quick lube will work.

Laziness gets expensive over time if you keep claiming I don't have time for this and that and the bike falls further into disrepair more and more will fail and you will spend a lot to get the bike working safely and properly again. Just take some time here and there to care for your bike or purchase a bike that requires a little less maintenance like a belt drive single speed.

Light rust can happen and certainly as a commuter in winter on roads that get heavily salted it is problematic but a quick lube and wipe will stop that and rising the bike off once and while will also help and cost little and take little time. I would say spending 10 minutes a week on maintenance which would leave you 10070 minutes the rest of the week will help you greatly or at the absolute barest minimum take those 10 minutes and do it monthly and you will still have about 43790 minutes left to do other things. And 10 minutes is a lot of time and you might find you can do it in less. You don't need a hose or special tools. You can wipe down your bike with an old t-shirt and some lightly diluted Dr. Bronners and put it in a spray bottle to make it easier and you can wipe your chain with that old t-shirt once the bike is clean and lube it with a basic bottle of lube from the bike shop, I like wax lubes personally and then maybe find another part of the t-shirt and wipe the excess. You can do this on the ground without a stand and without flipping the bike over just lean it on the corner of a wall or something and pedal backwards. Nothing fancy no tricks no advanced skills just super basic cleaning and lubing.

Take care of your bike and it will take care of you!

cyccommute 

I fully disagree. First, elfmachine heard audible pops during the soak. There is little that would make sounds like that other than the metal actively cracking. Second, the outer plate isn’t force fit over the pin…at least not with enough force to crack the outer plate. The pin and outer plate have to rotate relative to each other so the fit can’t be that tight. Most modern chains are peened over to hold the pin in place and even those that aren’t peened don’t experience significant incidences of cracking in normal use. Chain breakage, especially cracking of the plate, is a very uncommon occurrence in all of bicycling.

The “significant” qualifier is the problem. A very small volume of iron can produce a very large volume of rust. The rust between the inner plate and outer plate at the pin is what makes the chain “stiff”. One unit volume of iron is going to make 6 unit volumes of rust. A milligram of iron will make about 3 mg of rust but that rust is going to take up a lot more room. Essentially, a very small amount of iron loss would result in a very large amount of rust interfering with the operation of the chain.

I wouldn’t say that a rusted chain…even one that is stiff…is mechanically compromised. It’s not in danger of breaking even if put under significant load. It’s sounds horrible and it doesn’t move freely but a rusted chain could be ridden. The reason that people dispose of rusted chains is the difficulty of removing the rust. As elfmachine has found, common household chemical treatments may result in further damage due to the chemical reactions…not the physical reactions.

I have already said that it’s not worth trying to clean the chain but the chain isn’t in danger of breaking during use.

Clyde1820

Entirely possible that an aging chain had the rust attack it sufficiently that minor weaknesses became clear and obvious cracks here and there. You might never know.

I'm with the others, regarding which product choices to make. On a flat metal surface needing rejuvenation, a "rust remover" product is a good option, to begin getting rid of such crud. But on a mechanical moving thing like a chain, I wouldn't want a product to "dig" too deeply into the metal. A good de-greasing type product along with some moderate scrubbing would be a better choice, I'd think. And chains are inexpensive enough that instead investing in complete protection from the start will likely yield better results. Frequent salt removal, grease removal, displacement of water, re-greasing/oiling/waxing. In the end, though, it's a consumable.