E-mountain bikes, so-called eMTBs, are becoming increasingly more popular, as they enable trail rides that would normally be too steep, loose, or rocky for a standard bike, as well as allowing the rider to become faster on the climbs
The added torque of eMTB (mid)motors translates into increased chain tension and much higher rates of wear on the drivetrain, and in particular, on the chain.
Besides the bike’s tires, the chain is inevitably the component that demands most replacement activity - But how do you actually know when the chain is due for replacement?
We have interviewed a bike enthusiast and one of the Kindernay engineers, Jakob Deraas Grimsgaard, about all the facts that you need to know about the chain on your eMTB, and its proper maintenance.
E-mountain bikes, or eMTBs, are electric-motor-equipped bicycles that assist when pedaled. When you start pedaling, the motor is activated and gives the rider assistance, which ultimately allows you to climb up steep hills with much less hassle.
The bicycle chain transmits the energy from the pedals to the rear wheel. The chain is subjected to high tension loads, and also has to withstand all sorts of weather conditions.
According to Bicycling.com, the general rule of thumb is that the chain on an e-bike should be replaced every 2000 miles, so approximately every 3000km, but it is impossible to pinpoint an exact distance after which the chain is worn out – too many variables influence the time of replacement. From my own personal experience, I would say that the chain on your eMTB should be replaced approximately every 400 to 1000km.
Ultimately no wear ratio and replacement date are the same for all chains, just like no riders are the same; Tour de France riders replace their chains twice or even three times during the three-week race! So, the rate greatly depends on individual factors such as the riding style, terrain, treatment, maintenance, etc.
E-mountain bikes are characterized by the motor’s high torque, (and some added weight), which does increase the wear on working parts such as the chain or brake pads.
By being subjected to the added torque of the motor, the e-chain has to be replaced more frequently than on a regular bike. The bright side is that the electric motors do not add a lot of maintenance activities, such as oil changes.
Several measurement tools exist to determine the wear of the chain.
The simplest method is the ruler test. The necessary background knowledge for this tool is that modern chains have rivets every half-inch; the rivets to be measured are 12 inches away from each other. A new chain will measure exactly 12 inches across 12 links, from the middle of the first pin to the middle of the second pin, while a used chain will be elongated.
As a rule of thumb, you can say that anything past 12 1/16 inches (0.5 percent) is the time to replace the chain, to preserve the rest of the drivetrain.
Another method for measuring the elongation of the chain is using a special tool called a chain checker. By holding the tool in the hand, pressure should be applied to the pedal so that the chain is taut, then placing the ends of the tool into the chain. The tool’s wear indicator will thus determine if the chain has to be replaced.
If you ride for too long on a stretched chain and keep using the chain beyond the 0.5-0.75% point of wear, chainrings, and cassettes might be damaged, as they start to conform to the elongated chain, ultimately forcing you to replace those sooner than you should have to otherwise.
If the chain is replaced once the stretch reaches approx. 0.5% (or 1/16’’ elongation over 12 links, as described above), the same cassette can often last as long as five chains.
With some cassettes often costing hundreds of dollars, keeping an eye on chain wear and replacing the chain once the wear limit is reached, makes good sense.
Maintenance is key, so cleaning and lubrication are crucial!
Chain cleaning should be done frequently.
After every ride, you can quickly wipe surface dirt off the chain with a clean cotton rag. If the chain is more filthy, you can use a nylon brush to scrub the chain with hot water and liquid soap, but make sure that you lubricate it afterward. If the chain is super filthy, removing it from the bike and soaking it in a solvent (for example, Kerosene) makes sense.
The most thorough way to clean the chain is by removing it from the bike and soaking it in a degreasing solvent. With so-called quick links (which most modern chains have), removal and reinstallation can be done in seconds.
Always make sure to dry and lube the chain after cleaning, wiping away any excess lube.
As a concluding statement, I would always say that when you’re unsure about the condition of your chain on your eMTB, do replace it. It will potentially save you a lot of money in the long run, by not placing unnecessary wear on the other (often expensive) components of the drivetrain!
Thank you, Jakob, for all of these insights!
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