In October 2020, BMW announced the “M Endurance chain”, which they touted as being “maintenance-free like the shaft drive”.
“Maintenance-free” is true compared to traditional chains, but the term “maintenance-free” requires a few caveats, as nothing that moves and transmits power (and absorbs power losses) is truly “maintenance-free”.
After all, even shaft drives aren’t maintenance-free. You have to keep a shaft drive lubricated, make sure you don’t get water inside it when cleaning it, and eventually you can expect it to fail from wear (but hopefully after a very, very long time).
So yes, the M Endurance chain is maintenance-free like the shaft drive, i.e. to a similar degree. It’s not that both are absolutely free of maintenance.
BMW themselves refer to the M Endurance chain as a “low-maintenance” chain in their own motorcycle manuals. See this screenshot from the latest S 1000 R manual:
So given that “maintenance-free” needs caveats, I decided to go beyond the press release and figure out how it works.
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More about the BMW M Endurance Chain vs Traditional Chains
Visually, a BMW M Endurance chain doesn’t look strikingly different. (Yes it has a different colour scheme, but that is common on traditional metal chains too.)
The M Endurance Chain operates like most other chains in transmitting energy. It takes torque from the engine via the front sprocket, and transmits it to the rear wheel via the rear sprocket.
In doing so, it’s subjected to the same torque that any chain would be subjected to — nothing changes there. So it’s constantly being stretched and compressed and expected to politely not snap under pressure.
A BMW M Endurance chain is still an X-ring chain, just with an enhanced exterior coating.
In X-ring chains (the chains on most modern motorcycles, including recent BMWs), there’s a seal whose cross-section is shaped like an “X” separating the inner and outer plates.
The purpose of this X-ring seal is to keep grease in the pins and bushings and to keep dirt out.
The seal used to be an “O” (like most bushings), but the X has advantages in providing more torsional rigidity, reducing friction (less contact surface), and retaining the grease.
When you lubricate a normal chain, you’re NOT lubricating the inside of it. That’s sealed! The only way you’d be able to lubricate the space between the pins would be if a seal had broken, i.e. your chain had failed, which would be bad news.
What you actually are lubricating is the contact area between the rollers and the sprockets.
It’s really hard to keep this part lubricated. Many things work against you:
- You keep twisting the throttle, making the wheel spin around, flinging off the lubricant. Stop it!
- Dirt, salt, mud, rain (and rust), because we ride outside, not in vacuums
- Constant braking and acceleration, moving the chain around and allowing other things in
In old motorcycle manuals from the 2000s and earlier, manufacturers would sometimes just suggest using engine oil to lube the chain. Regardless of whether or not this is a good idea, it definitely is messy and risks causing stains on your floor, or flinging off onto the road under your tyre.
Ask on any forum and there’s debate (surprise) about what kind of lube is best (WD-40? Engine oil? Gear oil?) and questioning about whether lubrication is even beneficial at all if it just flings off.
So how the M Endurance chain is different is that it doesn’t need frequent re-lubrication of the outside rollers.
Most motorcycle chains are made of metal. The metal is smooth, but the smoothness wears off thanks to the outside elements.
M Endurance chains are coated with a diamond-like substance that is very tough and very slippery and doesn’t wear off easily and doesn’t need replenishing.
More below on how the BMW M Endurance Chain works.
Maintenance to do on the M Endurance Chain
Yes, you still need to maintain an M Endurance Chain. Just a lot less.
In BMW’s words from the press release, “the familiar ‘chain lubrication’ is no longer necessary, nor is any re-tensioning required from time to time due to the usual wear”.
This does not mean you never have to lubricate the chain, nor that you never have to adjust chain tension. It just means that you do those things a lot less frequently.
In most BMW (and other brand) motorcycle manuals, manufacturers recommend you lubricate and check the tension of a chain every 300-1000 km (200-600 miles), depending on the brand/bike. They also say you should do this more often if you subject your bike to harsh conditions — usually dirt, sand, and water, which can cause abrasion on the surface of the chain.
Maintenance intervals are a bit finger in the air, but essentially, chain maintenance on most bikes is something to do periodically, much more often than most service (oil changes and so on).
Depending on how often and how much you ride, on most motorcycles you may have to clean, adjust, and lube your chain as often as every week (or maybe more) for a commuter bike.
For the BMW M Endurance Chain, the chain maintenance requirements are much less stringent. You still have to lubricate the M Endurance Chain — but you lubricate it, at minimum, as part of your annual service.
The manual for the 2021 BMW S 1000 R (the manual for which came out after the BMW M Endurance Chain was announced), for example, says (separated into bullets for clarity, my emphasis added):
- The low-maintenance drive chain is cleaned and lubricated as part of the annual service.
- For optimum durability, the low-maintenance chain can also be lubricated at intervals by application of a chain lubricant suitable for low-maintenance chains.
- If riding involves above-average wear and tear due to exposure to salt or dust and dirt, carry out lubrication at correspondingly more frequent intervals.
(This is from the manual for the Jan 2021 BMW S 1000 R (0E53 USA), which you can get from the BMW website.)
Guidance from that same manual on how to lubricate the M Endurance chain is:
- Clean the drive chain with a suitable cleaning product, dry it and apply chain lubricant.
- To prolong chain life, BMW Motorrad recommends the use of BMW Motorrad chain lubricant or an O-ring compatible chain spray.
So in summary, on how to maintain your M Endurance Chain
- You still need to keep your chain clean.
- You need to lubricate your chain as part of your annual service.
- If you ride in harsh conditions (salt, dust, dirt), then clean and lubricate at more frequent intervals.
What you need to maintain your M Endurance Chain
So you still need to clean and maintain your chain annually, or when riding in harsh conditions.
To maintain your M Endurance Chain, you need something to clean the chain, and something to lubricate it.
An old-time favourite of many motorcyclists is a Motul chain care kit. This contains chain cleaner, brushes to wipe away grime (and a lot may accumulate between annual services! Or from your latest muddy adventure).
How does the M Endurance Chain work?
The BMW M Endurance Chain is still an X-ring chain. But the rollers and bushings are is coated in a diamond-like carbon substance that’s highly wear-resistant, very low friction, and that you very rarely need to clean and lube.
The M Endurance chain uses tetrahedrally amorphous carbon (ta-C), a form of industrial diamond or DLC (Diamond-Like Coating), to coat the roller and bushing.
In contrast to the metal surfaces used on most chains, the M Endurance Chain’s ta-C coating a) does not wear off, and b) has a drastically reduced friction coefficient compared to metal.
BMW describes ta-C in its marketing materials as being “harder than DLC”, but this is a simplified explanation. In truth, ta-C is a highly pure form of DLC; it’s just that we know DLC from other uses (e.g. it’s common as a fork stanchion coating on high-end bikes) and BMW is trying to say “our ta-C DLC is better than other DLC”.
All DLC coatings are made up of crystallised carbon with a proportion of crystalline carbon atoms in what’s known as an sp3 crystalline structure. In chemistry, sp3 hybrid orbitals form a tetrahedral arrangement. Carbon’s valency of four means that carbon can bond with itself in a tetrahedral fashion when the electrons are in hybrid sp3 orbitals, forming a diamond.
Carbon can also bond with itself in other structures, like sp2 for example, which is planar. A common instance of sp2 is graphite.
Most DLC coatings for mechanical use have a lower proportion of sp3, usually between 25-60%, due to the way they’re made and deposited, and possibly as a cost-saving mechanism (as making pure ta-C is expensive). Most DLC coatings are a good start, but are subject to wear under high pressure and temperature.
But the manufacturing process for ta-C results in a higher 70-95% proportion of sp3-bonded carbon, depending on the method used to deposit it. This results in a harder-wearing, longer-lasting, and lower-friction coating.
So the end result is that the DLC coating on the BMW M Endurance chain is likely to withstand a lot of abuse — but still, take care of it.
What motorcycles is the M Endurance Chain available on?
Initially, BMW made the M Endurance chain available for the BMW S 1000 RR and BMW S 1000 XR.
But from 2021 onward, it’s also an option on the new 2021+ BMW S 1000 R as part of the M package.
I hope to see it available on other chain-driven BMW motorcycles like the F 900 R and F 900 XR in the future, but time will tell.