Hydrogen Embrittlement, Can You Really Break a Chain?
We talk a lot here about certain degreasers causing hydrogen embrittlement and that they shouldn't be used to clean your drivetrain. That leads to a ton of great questions like "what is hydrogen embrittlement", "can my chain really break from simple green", and "is this just marketing hype to buy more expensive degreaser."
They are all fair questions and we wanted to explain what hydrogen embrittlement is, what causes it, and provide some real world examples of failures in the real world.
What Causes Hydrogen Embrittlement
Metal degreasers are very basic on the PH scale. The best ones have chemicals in them as well to buffer PH to keep them from dropping to a more acidic state. The reason there is because this drop in PH is what causes hydrogen embrittlement.
As the basic cleaner turns acidic, it frees an extra hydrogen atom that the steel of the chain will absorb. As the chain absorbs more and more hydrogen, it becomes weaker and prone to fracturing under load. In a chain this is a catastrophic failure that can lead to a chain breaking and will likely happen when the most force is being applied. Your sprint, going full gas up a climb, etc.
Why Do Companies Make Degreasers with Acid
A popular cleaning agent is citric acid. This is essentially lemon juice and is a really effective household cleaner. A product like standard Simple Green uses this because its main market is as a household cleaner, not bicycle chain degreaser. Its a great product to clean the stove top or other household appliances that don't have a strength requirement.
This can be seen in a VeloNews article by Leonard Zinn talking about the dangers of using Simple Green for chain degreasing. A representative from Simple Green reached out to confirm they would recommend the non-corrosive formula in their Simple Green Aerospace product.
Adding low PH cleaners to these all purpose cleaners also makes them a little less harsh on your skin so that could be another motivation behind making a more PH balanced cleaner.
Can Household degreasers be used anywhere on Bikes?
In short, no. When we began our project to create the Bicycle Spa family of products it was influenced by Josh's experience working with Team CSC so many years ago. They had a problem where bikes had paint peeling, hubs were being destroyed, and just about everything aluminum was falling apart after just a couple months.
It didn't take long talking to the mechanics who were raving about their purple degreaser and how well it cleaned. A quick look at the ingredients and they saw that the main cleaning agent was Sodium Hydroxide. Sodium Hydroxide is an extremely effective cleaner, but it is extremely corrosive to aluminum. They say a picture is worth a thousand words, but the video below should be enough to never spray this stuff near your bike every again.
Not only can these degreasers turn acidic and cause hydrogen embrittlement and break a chain, it could be corrosive to the aluminum parts on your bike as well. If your frame is aluminum, your hubs, derailleur, rims, etc. could all be ruined over time by using some of these general cleaners not intended for bikes.
What Degreasers to Use for Bikes
We have looked at some of the dangers of hydrogen embrittlement, what causes, why it damages components, but we haven't talked about what to actually use. Aerospace is a great place to look because while breaking a bike chain in a sprint can cause a lot of damage, planes and helicopters falling out of the sky are often fatal. There have been numerous reports of hydrogen embrittlement causing fasteners to fail in aircraft causing crashes.
These types of incidents led to an overhaul in the maintenance and cleaning of aircraft. While Simple Green gets a lot of the bad publicity around hydrogen embrittlement, they also make a Simple Green Aerospace product that is fantastic. The ingredients are completely different and it is specifically designed to clean metals while being non-corrosive and PH balanced.
This question of what is safe to use on bicycles is really what led to our launch of the Ultimate Brake and Drivetrain Cleaner. We wanted to produce a product that would attack specifically what we were looking to remove on bikes, leave behind what we wanted to keep, and most importantly not damage the drivetrain. So now there is an option that can remove dirt and oil but leave your chain wax on the chain. It will strip brake dust and rinse clean so you can eliminate squeal. You can also be confident that when you are really pushing on the pedals, nothing is going to happen to the chain.
A lot of what we do at SILCA is based around protecting the investment our customers have made in their bikes. We realize that cycling is by no means a cheap sport so hopefully we can avoid things like pre-mature chain wear by waxing the chain, we can avoid hydrogen embrittlement by using a safe degreaser, and even protect your carbon rims by using tire levers designed to be used on a carbon rim.
By taking care of that expensive bike it will ultimately make your ride last longer, save money, and ultimately let you spend more time in the saddle and less with the bike in a work stand which is what we are all after.
If you have questions about hydrogen embrittlement, corrosion, degreasing, waxing chain, or anything else that we covered, please leave a comment or reach out at email@example.com.
Ron, Simple green is not acidic. pH is 9.0
Simple Green has another product called “Pro HD” that is purple in color and specifically labeled as safe for metal surfaces and ultrasonic cleaners. It does however recommend not exceeding a 10:1 dilution ratio for surfaces requiring corrosion protection. Unlike the aerospace stuff, Pro HD is readily available at $16/gallon from Home Depot. Is there there anything known about how safe Pro HD actually is for chain cleaning?
though I agree acidic cleaners do and will cause hydrogen enbrittlement, I want to point out a few picky details, 1- the hydrogen in an acidic medium is not hydrogen but a hydrogen ion with a single positive charge due to the loss of an electron, since metals by their nature are electron donors this leads to the ionization of the metal that like rust corrosion can lead to the enbrittlement. 2- the term is pH not PH, where the lower case p indicates the negative log of the hydrogen ion concentration. Because hydrogen enbrittlement is a propagation event, use of ultrasonics can and probably do make the cracks grow faster. The bubbles one sees are cavitations which in fact are local implosions where the collapsing medium will generate a point source heat that is unbelievably hot (many thousand degrees kelvin). It would be reasonable to expect that cavitations would be preferentially generated near cracks and are known to cause pitting in metal (the pitting on a boat propeller are from cavitations). So I believe that acidic media (like Simple Green) and ultrasonics is a double whammy against the chain and could make the possibility of failure even higher.
Leave a comment