Technical Q&A with Lennard Zinn – Not-so-Simple Green
Dear readers,I am always amazed how a single reader letter can sometimes generate a flood of follow-up mail. Over the last couple of weeks I have received a good deal of e-mail about the potential problems people encounter when they soak chains in Simple Green for an extended period. Many of those notes focused on SRAM chains, and some writers suggested that it was the steel used in those chains that was the root of the problem.Now that I have learned a lot more about it, I doubt it. I believe that SRAM chains were mentioned most often simply because people who soak their chains for long
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By Lennard Zinn
I am always amazed how a single reader letter can sometimes generate a flood of follow-up mail. Over the last couple of weeks I have received a good deal of e-mail about the potential problems people encounter when they soak chains in Simple Green for an extended period.
Many of those notes focused on SRAM chains, and some writers suggested that it was the steel used in those chains that was the root of the problem.Now that I have learned a lot more about it, I doubt it. I believe that SRAM chains were mentioned most often simply because people who soak their chains for long periods of time in Simple Green are more likely to purchase SRAM chains. Why? Because they would need to rotate between two or more chains in order to soak one of them for an extended period, so they are more likely to pick a model that offers a master link. In this day of super-narrow 9- and 10-speed chains, you can’t open one without a master link and not risk failure. The point where the rivet has been pushed in and out is seriously weakened and you almost have to buy a SRAM or other chain that features a master link to be able to remove the chain and still use it again later.
I’ve read a number of theories as to why this cracking occurs and I am including a brief sampling of the letters on that topic in today’s column.
Wow, it really did happen
I sure didn’t believe that Simple Green eats chains, but then I went to the back of my car to examine the chain that exploded three weeks agoat a `cross race. Here I thought it exploded because I downshifted while standing and muscling my way up a hill.
Upon closer inspection, I found five cracks on the chain, four on one side, one on the other, one of them failed.
Take a look at the photos I am sending to underscore my point.
The chain failure problem after prolonged exposure to Simple Green, as mentioned in a recent VeloNews tech note, is probably causedby hydrogen embrittlement of the steel chain. This is also known as stress cracking corrosion.
I suspect that the cleaner gradually ferments, which reduces the pH from its normal mildly alkaline state to mildly acidic. Slow corrosion of the steel results, generating a little hydrogen on the surface. Anaerobic conditions also generate hydrogen and hydrogen sulfide biochemically and produce small amounts of methane.
The chain steel probably has sufficient residual stress both inherent from the crystal structure and also from chain plate stamping to be susceptible to hydrogen stress cracking, and this can be accelerated by the sulfide.
Lesson: Don’t leave the parts in the cleaner longer than necessary and discard cleaner which is no longer alkaline.
It’s the water
I don’t work for Simple Green, however I find it somewhat unlikely that it would cause a metal chain to crack. The only chemical listed on the MSDS is Butyl Cellosolve. This solvent is used as a degreaser. We have had Simple Green analyzed and they only ingredients are that, surfactants and water. There is nothing except the water to attack the metal chain. You should note that any good cleaner is basic, so there is no acid available to attack the metal.
Since the main ingredient is water, I would not recommend soaking a chain in it. Especially a ferrous based one, as you will get a rusty chain.Rusting does cause small pits to form and with time, maybe they will form a deep pit. Of course any water based cleaner will do this. If you already have a crack in metal and put a stress on it, a surfactant lowers the surface energy and allows the crack to grow faster. This makes it important to rinse the chain thoroughly.
As for finding cracks after soaking it, they were likely there already and on a clean chain were visible. Rusting in the crack would also make it show up better.
Michael J. Kubes
3M Home Care Lab
A new solution?
My name is Denise Dochnahl and I work for Simple Green. I’m writing because I recently read a posting about someone leaving his bike chain soaking in undiluted Simple Green for five months, and then having the chain disintegrate on them. I also read that something similar happened to someone else, after having left his chain in undiluted Simple Green for just two weeks.
I have received comments from other bicycle enthusiasts that have tried a new Simple Green product on their bikes and bike parts, and have had great success with it. The product is a little bit different – it was designed specifically for the aircraft industry, and has heightened non-corrosive properties. It has passed Pratt-Whitney specs and Boeing specs, as well as other testing protocols. This is very likely a much better product to use for the applications I read about on VeloNews.
While Original Simple Green is an excellent all-purpose cleaner/degreaser, it was not designed for long-term storage of bike chains or other parts. While we stand by the efficacy of the product, and believe it to be an excellent cleaner for bikes and bike parts, we feel we must stress the importance of using the product according to the label instructions. Under no circumstances should anything be stored in any formula of Simple Green.
The new product, called ExtremeSimple Green Aircraft & Precision Cleaner, has heightened non-corrosive qualities, making it perhaps more suitable for high-tech bike alloys, painted surfaces, rubber and plastic parts. To date we have only promoted this product in the aviation industry. If it turns out to be better for bicycles and bike parts as well, then we’d certainly like to let people know about that.
More creak, pop, click
Like the reader in last week’s column, I also have a clicking in my bike. It feels like it is coming from the crank/bottom bracket area. At first it felt like it was coming from one side and I thought it was the pedal (I, too, have C-Record Pro-fit pedals), but sometimes it comes from the other side. I greased the BB very well. The BB and chain have less than 3000 miles; the wheels and cogset are brand new; the cogs are tight.
What are the chances that both pedals start clicking at the same time?How do you rebuild them? And what else could it be? Something a bit odd is that it does it every other pedal stroke. Any ideas?
Both of mine usually get going about the same time, and for a while, it is not on every stroke.
Of course, the best way to rebuild them is to buy my book and follow the instructions.
Bike is completely replaced… except for the shimmy
My bike goes into a severe shimmy at about 24mph when descending with my hands off the bars. The faster I go, the worse it gets. It has done this since I bought it new two years ago. During this time, I have replaced the tires at least five times, used three different stems (100, 110, and 120 mm), replaced the front wheel bearings, replaced the wheels and even replaced the frame and fork. Despite all of that, the shimmy remains.
I have read all about why this happens and figure it might just be inherent to frame design, but two items I found on the web leave me wondering ifI should try a different fork:A report by Craig Calfee linking speed wobble to the symmetry of the fork dropouts.A more general statement that fork trail or rake affects speed wobble.This bike has a Litespeed fork with 40mm of rake. Do you think upgrading to a fork with more rake would help?
Certainly, the fork can affect shimmy, both by its alignment and by its rake. I have had success with reducing shimmy on bikes brought to me for repairs by increasing rake, but I would imagine it could also happen with an improvement in fork alignment. That said I want to warn you not to expect too much. Shimmy generally is a function of the flex in the frame, specifically torsional and lateral flex of the top tube and down tube, and there is nothing you can do about that other than replacing the frame or the rider.
For frames with very minor shimmy — meaning it only starts up at over 30mph and only with the hands off — I have been able to eliminate it by increasing the fork rake by around 5mm by “cold setting” it on a work table. (Of course, that was in the days of steel forks. With carbon forks, you would need to buy a new fork and since it may not help, you could be throwing good money after bad.) I imagine that, even though this reduced the fork trail and hence reduced the bike’s stability, it allowed it to absorb more vibration in the fork and hence transfer a little less to the frame.
As for a bike with very poor fork alignment, you can imagine that the misaligned fork would always have to be turned a bit in order for the bike to go straight ahead. If the wheel is being always pushed a bit sideways, I can imagine that there would be a certain amount of chatter happening, because of the front tire sticking and then slipping as it was pushed slightly sideways. If that happens at the right frequency it could add to a resonant vibration in the frame. Improving the alignment may also increase the effective rake. For example, if one blade is bent back relative to the other, fixing that can reduce shimmy.
But again, I have been through this with many bikes people have brought to me over the 24 years I’ve been in business as well as with my own bikes before that, when I was on the U.S. National Team. It was those problems that inspired me to become a frame builder, since tall bikes are more likely to shimmy, and I ride a 65cm frame. From all of that experience, I can tell you that if a bike has a bad shimmy, especially one that occurs with the hands on the bars or at low speeds (15mph) with the hands off, you will not get rid of it by changing wheels, tires, headsets, stem length, handlebar width, saddle position, or even fork rake or alignment.
Given that you’ve replace nearly everything on your bike, you may have but one option left. Since, a bike always shimmies worse under a heavier rider, you can improve the situation by putting a lighter rider on the bike.
Give it a squeeze
After my first encounter with high-speed shimmy, believe me, I’ve read almost all the letters on what is happening. However, the second time I encountered the shimmy (roaring down a hill at 45 mph), and after worrying I was about to lose control before finally coming to a stop, I started to wonder if there was a technical skill that I could develop to bring my bike back under control without a lot of road rash or broken bones.
I don’t know if it has any effect on the answer, but I ride a seven-year-old 59 cm Jamis Comet with a straight, aluminum aero-fork, deep dish rims, and an aero-frame, and it’s a strong quartering wind that has set up the harmonic both times.
In hindsight my thoughts were to brace my knees on each side of the top tube to see if I could break down the harmonic, but I’m a bit reluctant to try to get the bike to shimmy again. This last time, the shimmy seemed to get more pronounced as I slowed – I would have thought using the back brake to slow would also reduce the shimmy, but my experience tells me I was wrong on that.
Yes, squeezing your knees against either side of the top tube is the best thing you can do to damp the harmonic oscillation.
Technical writer Lennard Zinn is a frame builder (www.zinncycles.com), a former U.S. national team rider and author of several books on bikes and bike maintenance including the pair of successful maintenance guides “ Zinn & the Art of Mountain Bike Maintenance” and “Zinn & the Art of Road Bike Maintenance.”Zinn’s regular column is devoted to addressing readers’ technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Readers can send brief technical questions directly to Zinn. Zinn’s column appears here each Tuesday.