Why an E-Bike Chain Can Wear Faster Than a Normal Bike Chain

It depends. The references don't give a number. None of the sources saved for this page says an e-bike chain wears out a set amount faster. They do show where extra strain can come from, and what else decides how long a chain lasts.

Where the motor's push goes

On a mid-drive bike, the motor isn't in a wheel. It drives the chain instead, usually from in or under the bottom bracket shell, the part of the frame that holds the crank axle.¹

That means the chain and sprockets (the toothed cogs and rings) carry the motor's force along with yours. One reference says the power is applied through the chain and sprocket, and that mid-drive power is typically limited to protect against fast wear on the drivetrain.¹

A hub-motor bike is different. Its motor sits inside the wheel hub itself.¹ This page doesn't try to say how its chain wear compares.

What wear actually is

A chain doesn't wear because the metal plates get pulled out of shape. The main cause is the metal wearing away where each link pin rotates inside its bushing.² The same reference says this is not actually how chains elongate.²

Each joint is tiny. Every link has one, so the whole chain adds up. Once the joints are worn, the links sit farther apart than the teeth expect. The diagram below shows the order of events.

Dirt and lube matter a lot

Here's where the common belief gets complicated. A general bicycle reference says chain wear is strongly aggravated by dirt getting into the links. It adds that the lifetime of a chain depends mostly on how well it is cleaned and lubricated, and does not depend on the mechanical load.³

That statement is about bicycle chains in general, not e-bikes in particular. Still, it's a useful check on the idea that more force always means faster wear.

Another repair reference lists what affects chain life: riding style, gear choice, rain or snow, local soil, the lube and how it's applied, and the condition of the sprockets. It also admits that experts disagree on the subject.⁴

The same wiki page gives a rough range for ordinary bikes. Depending on use and cleaning, a chain can last only 1,000 kilometres (600 miles) in all-weather use.³ Treat that as a reminder that conditions swing the result a lot, not as a promise for your bike.

Parts made for the load

Makers have noticed the extra loads. Most drivetrain makers now sell chains, gears, shifters and hubs suited to the higher dynamic loads of e-bikes.¹

So a chain made for an ordinary bike may not be the match your manual calls for. Your own manual is the place to find out.

Questions worth asking before you spend

• Is the motor a mid-drive, or does it sit in a wheel hub? That tells you whether the chain carries motor force.
• Does the manual name a chain type or say the part is made for e-bike loads?
• What does the manual say about checking for wear, and how often?
• How does the bike get cleaned and lubed in the weather where you ride? Dirt is a big factor, as the sources above say.³

Own a chain already? The ruler and gauge checks show how worn it is. The care side lives in the pages on cleaning and on lube types.