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Chain Construction, Wear and Care

June 5, 2016
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Despite its perception as an unglamorous, insignificant and utilitarian part of the bicycle, the chain is something I’ve found to be one of the most interesting parts of a bike in regards to its design and construction.  It is a greatly under rated consideration in regards to performance, and far too often neglected in terms of routine maintenance.  On top of this, while there are many methods and techniques to caring for a chain, there are probably equally as many misconceptions about it.

Construction and Wear

The construction of a chain is unique in the grand scheme of all bike parts.  To start with, a typical modern chain that consists of 116 links, when taking into account side plates, pins and rollers, contains a very numerous 464 individual components.  This adds up to hundreds of metal-on-metal bushing interfaces.  While it is not uncommon to see a few elsewhere on a bike, there are far more on the chain than everywhere else on the bike put together and chain bushings see huge loads compared to other metal-on-metal bushings on a bike, and do so at largely varying angles of contact.

There are a number of different metal-on-metal wear surfaces in a chain link that effect performance to varying degrees – rollers and side plates, outer and inner side plates, etc. – but the one interface which dictates the overall wear of a chain is the surface where the inner plates contact the pins.  Chain wear is often referred to as chain “stretch”.  While this is a convenient term to help people get a general conception of what is happening to their chain as it wears, there is no way a chain can permanently stretch under human riding power.  The perceived “stretch” is caused by material wearing away from the contact area between the chain pins and inner plates, and thus causing a greater measurable distance from one chain pin to the next along the inner plates.

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An excessively worn chain. Note the grooves worn into the pins, and the wear to the holes in the side plates. Although the amount of worn away metal seems slight, this chain was left probably 4-5 times as long as it should have been.

 

The classic method of measuring chain wear is to actually measure the chain with a ruler.  If the chain shows an elongation of 1/16” over a 12” section, the chain is considered worn and should be replaced (though this figure varies slightly depending on the recommendations of the chain manufacturer).  This equates to an average of only roughly five thousandths of an inch (0.005”) of worn away material at each pin/inner plate interface.  At this point, the pin-to-pin distance of the chain has grown to the point that it is inappropriate for the pitch of the sprocket teeth, and there will also be an increase in lateral flexibility.  On top of a loss of performance at this point, the sprocket teeth will also begin to wear slightly due to the incongruity between the pitch of the chain and sprocket teeth.  If the chain is left to the point that it measures 1/8” elongation, it is most likely that the sprocket teeth on the most used cogs on the cassette will be worn to the point that they will not accommodate a new chain.  The sprocket teeth will have worn down in order to match the elongated pitch of the worn out chain, and as a result of this sprocket wear, a new chain will skip when drive torque is applied on these sprockets.

A more conventional method of measuring chain wear these days is to use one of the many available chain wear indicators available from various bicycle chain and tool manufacturers.  There are many different design methods for these, but the best (albeit rarest) of which are design to isolate pin wear from roller wear.  As far as my research dictates, only Shimano and Pedros are making tools of this nature.  Shimano claims their own chain wear indicators are designed specifically to accommodate their chains, and are the only ones that can accurately account for the lateral flexibility inherent in their Hyperglide chain design.  However, the relevance of different chain wear indicators on different chain models is another discussion entirely, and you are generally fine using any of the ones available from a major manufacturer.  The most important factor in chain wear indicators is that you actually use one.

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Shimano’s 9, 10 and 11 speed chains, respectively.  Note the improved forging on higher speed chains.

 

Durability

There is a long standing myth that as we add more cogs to the rear cassette, and thus make chains narrower, that the chains also become less durable.  However, the complete opposite is actually true in practice.  Making a chain narrower may make it less durable if we are trying to chop it in half with an axe, but that’s obviously not the conditions in which these chains operate.

To start, we need to pinpoint what is actually meant by “durability”.  When using the word in regards to a bicycle chain, we are talking about its resistance to wear as discussed in the first section, as well as the resistance to the chain actually breaking.

A chain’s resistance to wear is due mostly to the integrity of the interface between the inner plates and the chain pins, and to a lesser degree the interface of the inner/outer plates, and rollers/inner plates.  The narrowing of a chain does not actually compromise these interfaces in any way.  At a minimum, if were are merely shortening the length of the pins that hold the chain together in order to make the chain narrower, these interfaces can all retain the same area of contact.  Beyond that, advances in manufacturing and materials engineering have made chains longer lived in this regard.  Metal forming techniques have made more durable interfaces between the chain components, and we are now seeing coatings and surface treatments on chains such as diamond like carbon, nickle/PTFE plating, chromizing and titanium nitride.  This combination has led to a continuous increase in the wear resistance of chains as the number of cassette cogs increases.

Not surprisingly, many of the advances in metal forming and surface treatments that contribute to wear life also help the chain resist failure, in particular the better formed interfaces between pins and side plates.  Shy of a physical impact against the chain, chain failure is almost exclusively caused by the outer plates snapping off of the rivet pins, so a strong connection between those two parts is the key to deterring failure.  Again, this property is completely unaffected by the overall width of the chain.  Also, in contrast to another widely held misconception, hollow pin chains are actually stronger than solid pin chains.  On modern geared chains, when being assembled at the factory, the end of each chain pin is peened against the outer plate in order to strengthen the connection between the two of them.  Hollow chain pins react more favourably to this process since the hollow structure of the chain pin allows it to be more easily and effectively peened, which translates to a stronger chain.

Factoid: The most demanding event on the structural integrity of a chain occurs during a loaded up-shift of the front derailleur.  In this case, the chain is removed from the smaller chainring via a pickup pin which is used to smoothly guide the chain onto the larger chainring while maintaining power transfer through the drive train.  This chainring pin exerts a tremendous side load on the chain pin at the rear of the engaged outer plate, which in turn creates the greatest stress the chain will see under standard drivetrain function.

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Shimano, KMC and Sram 11 speed chains shown together for comparison. The KMC chain has voids in the titanium nitride surface treatment on the mating surfaces of the different chain components.  This leads me to believe the surface treatment is applied after assembly, and is primarily for aesthetics

 

Factory Lube

Chain lubrication is a touchy subject because there are so many variables involved in establishing what products and techniques work well for the combination of rider, conditions and components.  Fortunately there are a handful of principals that can help anyone figure out the best approach for their circumstances.

Every new chain, before it ever gets mounted to a bike, is coated with a factory lubricant.  There is a long standing myth that the grease on a factory fresh chain is a “packing grease”, which by definition is a grease applied to steel industrial parts to protect them from rusting while in storage or transport.  This is not what comes applied to modern bicycle chains.  The grease applied to a bicycle chain at the factory is generally applied to all the individual components of the chain before any of them are assembled together.  It is designed to function both as an assembly lube for the manufacturing of the chain, as well as a durable and effective lubricant for the chain once it is actually in use on the bike.

Since the factory lube is generally applied before the chain sees any assembly (though it has been speculated that some chains get dunked in factory lube after they are assembled), the lube is actually a solid film, rather than a liquid drip lube that is most commonly used as aftermarket lubrication in order the help get oil into parts of the chain where it can’t be reached otherwise.  This means that the factory lube on a chain is both very durable, and very clean.  Most manufacturers recommend that on a new chain you do nothing more than wipe the outside of the chain with a mild degreaser in order to keep dirt from being attracted to the chain, but leave the factory lube in the chain until it wears off.  The down side to factory lube is that it is not the best lube in regards to drivetrain efficiency.  It’s said that as much as five watts can be saved by stripping the factory lube from the chain, and switching to a high performance liquid lube.  The hassles of this operation generally do not justify the benefits for the average recreational cyclist, but it is worth noting for someone looking for race-day performance.

One assertion I have heard echoed from many mechanics, including myself, is this: Too much lube is just as bad as no lube at all.  When chains come into my shop that are worn to complete oblivion, an equal number of them look to have never seen a drop of lube, as have been assaulted into a sticky, black, sludgy mess.  The reason for this is that as the bike is ridden, lube collects dirt, which turns the lubricant into a grinding compound within the chain.  In order to shed the dirt, the lubricant  needs to wear itself out of the chain, or the chain needs to be properly cleaned.  Continually lubricating the chain without cleaning it or allowing the old lube to wear off will trap dirt in the chain, and be counter productive in the long term.

Aftermarket Lube

In terms of after market drip lubes, there are two basic categories:  Wet lubes and dry lubes.  It is important to remember that “wet” and “dry” do not refer to the conditions in which the lube is optimized to perform in, but rather the actual properties of the lube itself.  It is true that dry lubes are generally more suited to dry conditions, and wet lubes are more suited to wet conditions, but this is not an exclusive distinction by any stretch.  Furthering this confusion is the fact that if a manufacturer creates a dry lube for wet conditions, they will rarely call it a “dry lube”, and the same applies to wet lubes for dry conditions.  It is common for manufacturers to avoid using the terms “wet” or “dry” when referring to their lubes to avoid any misconceptions or assumptions people may associate with those terms, as with terms like “wax” and “PTFE”.

Wet lubes, as the name suggests, remains in liquid form once applied to the chain.  The most tenacious wet lubes are lubes that are highly viscous, and often have tackifiers added to help keep the lube from washing off.  This breed of lube is very durable and targeted towards riding in extreme weather conditions.  However, it must be cleaned very frequently, as the same traits that allow this lube to stick so well to the chain also make the lube prone to collecting dirt.  If the dirty lube is not cleaned from inside the chain regularly, it will created a grinding compound and end up being worse than using no lube at all.  Generally speaking, heavy weight wet lubes are only a good option for a very small percentage of riders who ride in very wet conditions, and are very particular about cleaning their chains regularly.

Light or medium weight wet lubes, as one would expect, are less resistant to wash out, but require less frequent cleaning.  For many riders, these lubes may never require cleaning beyond a quick wipe with some degreaser on a rag.  On top of the fact these lubes rinse out of the chain quicker, dispelling any contaminants along with it, they also do not attract as much dirt as the heavier lubes.  Most riders can get away with using one of these lubes for moderately wet weather riding if they don’t mind re-applying the lube after every ride.  Another benefit of these lubes is that upon application, many of them help clean dirt out from inside of the chain, allowing the user to easily wipe off the dirt that surfaces once dripping the lube on.  Many lubes (such as the ubiquitous Tri-Flow), in fact, employ solvents to further help break down and channel dirt, as well as help get the base lubricant to the chain innards more effectively.  Lighter wet lubes also tend to be effective as a general purpose lube for a variety of bike applications such as shift mechanisms, derailleur pivots, spoke nipples, as a mild penetrating oil, etc.

Dry lubes, although more commonly perceived as a lube for fair-weather riding, can range in application from very dry conditions to very wet conditions.  The principal behind a dry lube is that the lubricating agent is carried into the chain via a solvent.  The lubricating agent will form a dry film on the chain, while the host liquid will completely evaporate.  Because of this process, dry lubes almost always need to be applied 6-12 hours before riding in order in order for the lube to get to its optimal state, although there are some dry lubes that are best put on immediately before a ride due to them containing pressure-activated additives (notably Dumonde Tech Lube).  Dry lubes also require the most thorough degreasing before application, and they may require a few applications before the lube fully “adapts” to the chain and performs optimally.  Failure to allow the lube to cure properly or degrease the chain properly will likely leave the drivetrain as a gummy mess.

The main benefit of a dry lube are that they tend to stay the cleanest, due to the fact the dry film formed as the lubricant is very impervious to collecting dirt.  This is a particular asset in very dusty conditions, where the fine dust particles can contaminate any wet lube almost instantly.  Although dry lubes on the whole are not known for their life span, there are many that form waterproof films that can stand up very well to wet conditions, as well.  Wax lubes are a sub-sect of dry lubes, which are known as lubes that can stay remarkably clean while providing excellent drivetrain efficiency, although they are renowned for being fairly short lived.  Generally speaking, wax lubes cannot be counted on to survive a full ride in wet conditions.

On top of the obvious matter of riding conditions and general chain maintenance to take into consideration when picking a chain lube, the actual model of chain is also an factor in what will work well.  With chain manufacturers constantly advancing their surface treatments to make the chains as hard as possible, combined with the never ending battle to fight friction, many chains compromise their ability to retain aftermarket lube in order for the chain to have better inherent wear and friction properties.  What lube works well with different chains is a bit of a trial and error process.  The lube that works excellent on your bike with a DLC plated KMC chain may not work as well on your other bike with a Sil-Tec plated XTR chain.

All this information on lube may be begging the question of “Where do I start?”  Well when recommending general application lubes, I tend to direct people towards a light or medium weight wet lube.  These are simply the lubes that require the more basic maintenance.  For most riders it’s just a matter of wiping the chain off, lubing, and re-applying when the chain dries up.  They also don’t necessarily require a thorough removal of a chain’s factory grease before applying.  The need for regular and thorough cleaning with a heavy lube is more involved than most riders care to deal with, and the more involved application process of a dry lube can require a level of attention and scheduling that many people just don’t care to commit to.  A light duty wet lube can be applied days before a ride or immediately before a ride with no sacrifice in its effectiveness.  This is not to say I don’t recommend other lubes for particular riders in certain applications, but my default recommendation is typically of the medium weight wet lube variety.  An attentive trial and error process is the only way to find what works best for you and your riding conditions.

Matt Faulkner was born in North Bay, Ontario, where he started mountain biking and racing downhill at the age of fourteen. He completed a diploma in Mechanical Engineering Technology at Georgian College in Barrie. After spending a few years in the engineering departments of mining companies, he switched over to the bike industry. He now lives and works as a bike mechanic in Downtown Toronto.

4 Comments

  1. Nice write up Matt. well done.

  2. I think Matt has learned the bulk of his chain knowledge dealing with my perpetually trashed drivetrains. Good article!

  3. Killer content as always dude.

    What about T9 esque light wet lube that leave a “waterproof” layer of lubrication? Do most light lubes do this? Is it similar to dry lube in that sense?

    I know you love data and here is a ton of well-thought-out data on corrosion resistant oils. http://www.dayattherange.com/?page_id=3667

  4. Hey Parker. Good to hear from ya. Good article. Lots of interesting points and experiments. The one caveat I have with it is that, altough an exceptionally valuable article, it may not be entirely practical for bicycle chains. A bicycle chain bushing interface endures a pretty significant load, and each chain can potentially see over a million cycles, which is somewhat different than many applications for a general lube. Also, rust prevention is not a key criteria, as most higher end chains have surface treatments that are rust proof to begin with.

    I have no experience personally with Boeshield T9, but it’s one that is one my bucket list to experiment with. I’ve heard good things. However, I’ve always known it to be a dry lube. On top of being referred to it as such by people in the industry, their website states: “T-9 dries to a clean, waxy, waterproof film that won’t wash off in rain, puddles or mud.”

    Lighter weight wet lubes would be something like Tri-Flow, which has a mild amount of solvent for penetration, and has solid PTFE suspended in it. But it does not dry to a film. No light weight wet lubes are “waterproof” as as far as I know, though that term is pretty vague when taking into account the other tasks and variables involved in a bicycle chain’s operation. I’m pretty sure any lube will wear off faster in rainy conditions than in clean, dry conditions.

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