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The drivetrain (chain? gears?) of my E-bike started to make loud clicking sounds, with the impression that the chain is skipping over teeth. The gear switching itself still works well.

I have tried to regulate the rear gear mechanism by adjusting the position screws but failed to make any improvement. The chain seems positioned properly.

I started to think, maybe some parts would require replacement. Could this possibly be for the bike that has been traveled only 400 km so far? It was rather cheap for E-bike from the other side, and on flat terrain it was mostly used on the same (fastest) gear.

Could some parts be already worn if low end? If so, which parts are likely to be?

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    At the end of the day, the answer to "My new bike doesn't work properly" is to take it back to the shop and get them to fix it. A good bike shop should also be offering a free service after, say a month, to make sure everything's adjusted properly. Of course, it's always educational to find out how you'd diagnose and fix it yourself. – David Richerby Mar 23 at 20:31
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    An E-Bike should definitely last more than 400km, unless it is a cheap plastic toy for indoor use by children After all, it's a motorcycle, just not with a internal combustion engine but an electric one. This is in contrast to a Pedelec ("Pedal Electric Cycle") where the user is intended to propel the bike with the pedals, with some assistance from an electric motor. A Pedelect is built quite similar to a regular bike - and therefore shares the same weak points. Specifically, the bearings. A failong bottom bracket (to which the crankset ("the pedals") is connected) emits loud clicking noises. – Klaws Mar 24 at 15:30
  • @Klaws Most things that people call "e-bikes" are what you call a "pedelec". But what difference does it make? Any e-bike, pedelec or ordinary bicycle should last more than 400km. – David Richerby Mar 25 at 22:08
  • @David The difference is that a "true e-bike" (like, for example, the Super SOCO TS1200R, motor power 2.4kW) has no "human factor" in the drivetrain. It will not deliver any more drive prower into the mechanical drive parts than it's rated for. A pedelec is different, it has pedals. And it's probably meant for the more lazy riders, who can add maybe 0.1kW of power to the motor power of maybe 0.25kW. A "trained amateur" can easily deliver a longterm 0.2kW (much more shortterm), and a pro can exceed 2kW. An enthusiastic biker can put much more stress on the drivetrain than it was designed for. – Klaws Apr 1 at 12:16
  • @Klaws I'm aware of the differences. My question "What difference does it make?" was specifically about the "My bike broke after 400km" aspect of the question. Whatever type of electric two-wheeled vehicle it is, it should be lasting much longer than that. – David Richerby Apr 1 at 12:24
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Yes it can and I've seen it before, but the problems you describe sound like issues which could be fixed with a simple gear tune rather than being caused by worn-out components.

The only one that I've seen wearing out that quickly could largely be blamed on the riding style of its owner. He was a heavy rider and reasonably strong, so he was someone who would put more stress on any drivetrain. He also had a tendency to ride with the motor on full assist at all times to allow him to get over any hills without having to shift out of the 11 tooth cog at the rear. The load that he was putting through the drivetrain combined with the tiny cog taking all of the stress meant that components wore out very very quickly.

He came in for new chains and cassettes (couldn't just buy a new 11 tooth unfortunately) a few times before I found a cheaper, more permanent solution for him. We replaced the chainring with a much bigger one and put on a cassette with a 13 tooth as the smallest cog.

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I have tried to regulate the rear gear mechanism by adjusting the position screws but failed to make any improvement.

That's almost never the adjustment that the rear derailleur needs. Those screws are called the limit screws, and they set how far in and out the derailleur can move. All they do is stop the derailleur from moving the chain all the way off the cassette on either side. There's basically nothing that causes those screws to move on their own so, assuming they were set correctly when the bike was built, they should almost never need to be touched. The symptoms that do mean they need adjustment is that either the chain is falling off the top or bottom of the cassette (derailleur able to move too far) or that gear changing is just fine, except that you can't change into the smallest or biggest cog (derailleur not able to move far enough).

The correct adjustment is to use the barrel adjuster to get the correct cable tension. That very often is needed on new bikes, because the cables tend to stretch a bit after they're installed. Argenti Apparatus has already posted a video so I'll not go into more detail than that.

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    What he said. New bike need readjustment on a regular basis. Even high end race bike need it. It certainly shouldn't be replaced after only 400km – ker2x Mar 23 at 23:00
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Even for a low end eBike using 400km will not wear out drivetrain parts.

If the chain was slipping over the sprockets, you would feel the cranks and pedals slipping forwards. This tends to be sporadic and makes a loud clang or crunch.

If you are hearing a periodic ticking, It's likely the rear derailleur indexing needs adjustment. From your post it sounds like you adjusted the limit screws rather then the indexing barrel adjuster.

Try following a derailleur adjustment procedure and see if that fixes the problem.

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    I have worn out a singlespeed chain in 800 km so I wouldn't completely rule it out. – ojs Mar 23 at 22:19
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I finally brought the bike to technician who discovered that the gear switching cable does not move freely enough (gets stuck). This is why I was not able find the good positions for any screws I attempted to adjust. Regardless of my desperation, the components of the gear itself were not worn, hence I leave the accepted answer as correct.

As for now, when I discover the gear mechanism going crazy again, I simply shift the gear from highest to lowest few times, "exercising" the cable. So far this always helps. Maybe the problem will go away by itself.

It is also true that I almost never use any other gear apart the fastest one, because of the flat terrain, so the cable does not see much usage.

  • Hmm. If the cable is sticking on a brand new bike, it is defective and should be replaced, free of charge. Either the cable is corroded (unlikely on a new bike) or the outers weren't rounded after being cut and they're pinching the inner. (The outers are cut with a cable cutter, which flattens then to an oval profile; you're supposed to poke something round into the cut end to fix that.) – David Richerby Mar 31 at 8:50
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Take the chain off and thread it through the rear derailleur properly.

It happened to me - there is a small guard near the top cog and the bottom of the rearderailleur, I threaded my chain on the outside of it (easilly done) chain slipped as described.

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    What makes you think this is the problem? If there was a problem with the way the chain has been put through the derailleur, the problem would have existed from day one, not started later. – David Richerby Mar 25 at 22:10

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