Archive for the ‘Tech Talk’ Category

Part of being a sustainable bicycle component is having a long life span, or at least having a long life span worked into the design. Failure analysis is an important aspect of the design process in order to gain long life span. For parts or components that undergo load, a good design process usually involves failure analysis after the testing phase. A lot of this happens in the bicycle industry. Many bicycle and component manufactures have an entire branch of their company that tests their product to a point of failure, learns from that failure, and works that knowledge into the continued design. If the company does not have a testing department, they contract the testing out to a third party such as EFBe. Another important reason that frames and components are tested is to make sure they meet certain safety standards, or performance standards. This kind of testing usually doesn’t lead to failure.

Cycling is a good place to find failures after the product has hit the shelves. The reason for this is that the weight of the final product is an important design parameter. So important that vast amounts of research go into removing mere grams off of components. Jobst Brandt said it well: “Parts which give reliable service are often considered “overbuilt” and are redesigned to save a few grams.” Unfortunately other design parameters are sacrificed to obtain desired weight. These can include ultimate strength, fatigue strength, and lifespan. Visit Jobst’s article Some Bike Failures to see more photos of failures and some more discussion as to the reason why bike parts fail.

Failures are seen on just about every part of a bicycle,  but one of the most common failures that I see on a regular basis as a mechanic is pitting of bearing races such as this one:

Pitting on a axle cone

This pitting can happen when abrasives contaminate the grease surrounding the ball bearing and race. Put simply, a ball bearing is sandwiched in between two smooth surfaces that are parallel to each other. These surfaces are called “races”. Since it is almost impossible to get the two races perfectly parallel, the ball bearing is always a little bit closer to the races at a single point in its rotation around the surfaces. The space between the ball and race is filled with grease, so when this grease is contaminated with abrasives, the abrasives get compressed against the race and the ball at the point in the rotation where the ball is closest to the race. When this squeeze happens under load, with thousands, upon thousands of rotations, it causes the pitting you see in the picture. This is a common failure and is the result of poor maintenance and poor bearing adjustment. With proper maintenance and adjustment, bearing systems of this type will last longer than their modern brethren.

Modern bearing systems are usually sealed. This means that the two races and ball bearings come in a neat adjustment-free package that just needs to be pressed and seated into a recess, like this:

You can see two metal rings. These are the races. The balls are under that blue piece of plastic. When these types of bearings get contaminated and go bad, you remove them, throw them in the recycle bin, and put in new ones. To maximize their life span they must be installed correctly (parallel and seated), and carefully wiped clean every now and then. You want to be careful as to not push contaminants beyond the plastic seal.

Once in awhile I’m blessed with an uncommon failure. Recently I was working on a Masi Gran Criterium that was upgraded in 1985 to full Campagnolo Super Record components. The rear derailer (1984 Super Record) had a small crack in its outer cage:

Cracked SR outer cage

This is a strange spot for a crack failure since this part of a bike is under minimal load. Since the crack lies at the back of the cage, then the maximum load scenario would be when the chain is in the big-big combo. This would place the tension spring at its maximum potential to compensate for the lack of slack in the chain. In other words, the derailer would look like this:

Big-Big Combo - Tension spring at maximum

When the derailer is in this position, the tension spring is counteracting the chain by trying to pull the tension pulley back to its neutral position. This puts tension on the back surface of the pulley cages. If you have trouble visualizing this, imagine the bottom surface of a beam under load. This surface is in tension while the top surface is in compression. In this scenario the back of the cage is in tension and the front of the cage is in compression.

Now, I don’t think that this is the only factor that caused the failure. In the picture of the cracked cage, you see a nut recessed into the cage where the spring cage bolt screws into. When the bolt is tight up againast that nut then there is a portion of the cage that gets compressed. The cage material is a very lightweight aluminum alloy, and when compressed with a recessed nut that has 90 degree angles for edges it will develop microscopic cracks. Points like this are called stress risers. To get a better look, I pulled the cage apart at the crack:

Notice the nut seat has a 90deg angle at the compression point.

The thin part of metal that is below the nut seat in the above picture is compressed when the derailer is in use. The angle between this section of material and the non-compressed material is around 90 degrees. At the vertex of that angle, the compressed material is being pulled away from the non-compressed material forming a high stress point which, over time, will develop microscopic cracks, especially in lightweight aluminum alloy.

Add one more factor to the mix, and it all becomes clear. Material flaw. There is a good chance that this part may have had a flaw on its back outersurface, such as impurity or void. I didn’t see any evidence of one, but I don’t have a scanning electron microscope at my disposal, so I may never know. It is, however, likely.

Design flaw, material flaw, and one too many times in the big-big combo sent this derailer cage to the graveyard. The problem is I don’t know the history of the bike, the rider, or when the crack developed (my customer just bought the bike), so I don’t know if it had a long life or not. I do know one thing. The bike it was on did not get ridden all that much. This crack may have developed in 1985 for all we know.

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I’m in the process of moving into my new place in Monterey California (hence the lack of substantive posting lately) and part of the whole process is getting my shop set up in my garage. I’ve built a few things in my past from wood, like some skating ramps in my high school days, and a chupah when I got married, but nothing as precise as my new garage shelves and workbench. I was going over in my head whether or not my workbench fell under the sustainable umbrella, and I concluded it did for a couple different reasons. First, if your going to be working on your own bike, you get to select which products your going to use, whether its for cleaning, lubing, components, or even tools. In order to work on your own bike comfortably, you’ll need some sort of work bench. You can buy a workbench or you can make one. If you make one, you can select all your own materials. For example, if your going to build your bench from wood, you can select FSC certified wood. You may also choose to build your bench from recycled material, such as RPL (Recycled Plastic Lumber), or reclaimed steel. You get the picture. Besides, it’s also good to know how to build basic things, such as a workbench. There are thousands of “how to’s” on the web on how to do this, but if you want a plan, you usually have to buy it. Here is one that I drew for free. My bench is 6 feet by 2 feet and 38 inches high, but you can adjust these dimensions to suit your needs. I’m about 5’11” with a 32″ inseam, and 38″ is just about perfect. Have fun!

The pictures below are of the workbench I just built. Most of the wood used is FSC certified. I say most because I’m not sure about some of the 2×4’s. The sign said they were certified, but after the purchase, I realized the tag didn’t look like the tag on the certified 4×4’s. I used Liquid Nails Heavy Duty construction adhesive at all the joints and between the two courses of plywood at the top. Maybe not the greenest product out there, but its the same stuff used to put LEED certified buildings together. If you decide to use RPL you’ll need a different adhesive. The vise is just a basic 41/2″ vise held on with three 3/8″ bolts, and one 3/8″ 3″ long lag bolt. After I took these photos I installed a surge protector onto the front of the bench. I may also make some additions to it in the future to hold certain tools.

Here are the photos as well as the plans free for you to use. Its supposed to be one sheet, but my scanner can only do 8.5x1a. The original is 11×14.

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As cyclists we all need to get parts for our bike at some point, whether its a headset, stem, seatpost, etc.  Things wear out, or break, and we either head to the parts bin in our garage, at the local bike collective, an online retailer, or local bike shop.  If you decide you want to buy a new part, then you have the opportunity, as always, to vote with your dollar.

Aluminum alloy is used more than any other material to make bicycle components.  There are very good reasons for this.  It is light, strong, durable, corrosion resistant, and relatively easy to work with.  Another thing a component manufacturer can do to their aluminum alloy parts is anodizing.  Anodizing aluminum alloy is a process of which the end result is an increase of durability, corrosion resistance, and wear resistance.  Another side benefit is the material can be dyed if it is anodized.


So, if you see colored aluminum parts, they have been anodized.  Take Chris King headsets and bottom brackets for example.  They come in a wide variety of colors.

From a design standpoint, anodizing makes a longer lasting product, but at what cost to the environment?

The process: To anodize a piece of aluminum or aluminum alloy, the piece is placed into a bath of acidic solution and a electric current is passed through it.  The piece acts as the anode, thus the name of the process.  The most common acidic solution used in this industrial process is sulfuric acid.  While the current passes through the piece, an electrochemical process takes place, resulting in a coating of aluminum oxide.  Over time, this would happen naturally to the aluminum, but this process ensures it happens evenly over the entire surface.  Because this is an industrial, electrochemical process, there is industrial waste in the form of liquid and gas.  The anodizing process involves, cleaning, rinsing, deoxidizing, anodizing, coloring, and sealing.  All of these have waste products, but the majority of the waste is created from the anodizing bath.  Hydrogen gas is produced during the reaction, and at some point, the acidic solution needs to be regenerated, or swapped out, generating waste acidic solution.  If the anodizing takes place in pure sulfuric acid, it can be neutralized and disposed of quite easily, but there is no guarantee that pure sulfuric acid will be used, and if it is, that it will be completely neutralized before discarding.  True, anodizing isn’t the worst thing for the environment, but if one company does it responsibly, and another doesn’t, I know which one I’ll choose.  This short video will show you some of the process.  At the end, you’ll see some badges of bicycle component companies.  They may have this particular company do their anodizing, or at least their nameplates.

The Good News:  The industrial process of anodizing can be contained where as almost no industrial waste is produced.  There are a couple patented anodizing processes out there that result in very little, to zero industrial waste.  It reuses by products, and adds a couple more reactions to either reuse chemicals, or create chemicals to be used in other processes.  Unfortunately, these zero waste process’s are more involved, thus more expensive.

Chris King has taken its anodizing into their own hands, and claims to use a zero waste water process.  This is a step in the right direction, and will hopefully become the standard.  I guess this is one of the reasons they’re parts cost so much.  I attempted to contact Cane Creek and Thompson to see what process they use, or what company they contract out, but I haven’t heard back.  I’ll update the post when I find out.

Anodizing is a common procedure for aluminum parts and aluminum alloy parts.  Stay tuned for Tech Talk articles on aluminum itself, and other common materials found on bicycles.

UPDATE May 22, 2009:  I’ve received word from Cane Creek about their anodizing.  They were kind enough to send me information on anodizing their 110 headsets.  A couple things impressed me about their process, including not using a polishing finish or aka, a “Bright Dip”.  I did a little research on what this was and found out there are many different types of Bright Dips, but all of them involve toxic and caustic chemicals.  From my understanding, this Bright Dipping is done to give the part a polished look, and is not necessary.  Clearly, this is something I need to watch out for when it comes to other companies.  The waste’s generated at the 110 headset anodizing process are typical, and include some solid waste and affluent.  The solid waste may include metals which are recycled, or disposed of, and the affluent is tested twice quarterly to ensure it meets standards for municipal wastewater.  I was also informed, that this wastewater is sometimes in demand since one of the things in the water is aluminum hydroxide which can be used to separate out solids at waste water treatment plants.  Are you industrial ecologists out ther reading this?  They also use organic dyes for coloring.  This means that they are not synthetic, or created by some chemical process.  As I hear back from other companies, I’ll keep you updated!


Industrial Waste Treatment Handbook, by Frank Woodard

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This article was fist published on Sept. 24, 2008 in my personal blog Its All One Big Adventure. All aspects may not be sustainable, but if you have these things in your garage or basement, there’s no need to go buy a new tool!

Bicycle tools are somewhat expensive. If your like me and don’t like paying for labor you can do yourself, but don’t want to buy tools that you might be able to make a lot cheaper, then you’ve come to the right spot. I have made a few tools from stuff you can buy at any decent hardware store. Just about all of these tools have been made in some form or fashion before this, so I’m not claiming anything, I just want to share my knowledge.

Headset Cup Remover: This one is easy. Take 12″ piece of 3/4″ copper tubing and cut two slits about 4″ long as on-center as you possibly can. (You can also cut just one slit, but you sacrifice having even pressure on the cup when you go to smack it out.) In other words, the slits should have the same distance between them on both sides. For cutting I use a craftsman version of a dremel tool, but a hack saw and vice may work as well. When your happy with the slits, carefully separate the two prongs. Copper has a low yield strength, so take care in separating the prongs. You want to try to bend the full length of the prong as opposed to just at the joint. At the end of the tube you want the separation to be enough so you can slide the 3/4″ uncut end into the head tube and pull the prongs into the head tube until you hear the tool “click” into place. One or two hard smacks with a hammer will pop your cups right out. The copper will not damage steel cups no matter how hard you hit it, so don’t back down. The less hits to remove the cups, the more times you’ll be able to use the tool. Copper is soft and will deform when you hit it so you might be able to get two or three uses out of one piece. If you plan on removing cups on a daily basis (or more than just a few times) buy a remover tool. Once I start removing cups on a regular basis, I’ll switch over to a real tool, but for now, that length of copper tube sitting in my shop is good enough. Here’s a photo of my latest one. Its a one slit deal.

Single Slit Homemade Headset Cup Remover

Single Slit Homemade Headset Cup Remover

Fork Crown Race Setter: A crown race must pressed or tapped down with even pressure all around it. For 1″ steel forks I use a 1″ copper sleeve and a 1″ by 24″ steel pipe. Grease the race, slide it into place and twist it while putting downward pressure. By doing this you should be able to get it started onto the crown evenly. If it didn’t happen evenly all around, start over or skip this step. Next, slide the copper sleeve onto the steertube, and then the steel tube. (A 1″ piece of steel tubing typically has an inner diameter of 1″. A 1″ steertube typically has a outer diameter of 1″ so the tool should slide right onto the steertube.) Turn the whole thing upside down, center the copper sleeve on the race, hold the fork blade and steel pipe in and tap until the pipe on the groud (or floor) until the race is fully seated. Sometimes a slam is required to fully seat the race. Here is photo of my trusty tool.

Homemade Fork Crown Race Setter

Homemade Fork Crown Race Setter

Headset Press for 1″ Headsets: This can be made using a 3/4″ stainless steel piece of all-thread, brass bushings, washers, and nuts. The bushings must be softer than steel, so brass is a good choice because it is a copper alloy, and bushings will typically come in plastic, rubber or brass. Bronze is fine too (it is also a copper alloy) so if you find bronze bushings, your good to go. The size of the bushings should be 3/4″ inner diamter, 1″ sleeve diameter, and 1-1/4″ flange diameter. A good hardware store should have this size. The press is to be constructed as shown in the photo below with the head tube and headset pieces in between the brass bushings. All headset cups are a bit different, so when setting up the press, experiment to see if the sleeve end of the bushing, or the flanged end of the bushing fits on better. More often than not, I find the flanged end applying the pressure to both the upper race and lower race to be the way to go. Assemble and slowly tighten one nut while holding the other in place.

Homemade Headset Press

Homemade Headset Press

Dropout Alignment Tool: Start with two steel eyebolts, four nuts, and four stainless steel washers. I use 3/8″ eye bolts that are about 8″ long. 3/8″ translates to about 9.5mm, so they are just a hair too big to fit into front fork ends. To fix this, I ground off as close to 0.25mm on each side as I could making flats on either side of the bolt. I recommend lining the flats up with the eyelets so that your eyelets are parrallel when installed on the fork. I also ground the threads off the end of the bolts so they would not get caught on each other if they happen to overlap (this would happen in a serious case of dropout misalignment.) Rear dropouts are typically 10mm, so fit is not a problem. Just make sure you have them seated as far back as posible. Here is a photo of mine:

Homemade Dropout Alignment Tool

Homemade Dropout Alignment Tool

Other Frame Alignment Tools: I’ve also used a 2×4 and a piece of string to align rear triangles. Use Sheldon’s cold setting method.

Other Homemade Tools: I’ve heard of people making their own repair stands, and truing stands as well. I can imagine how this is done, but I have not done it. I bought both.

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