I don't know what todo anymore.

The chain is sliding from the front chain ring when I'm not actively pedaling. When I'm actively pedal, it does not slide off.

The chain is not a week old, and it's the same as before.(for sure) Thought it was the front chain ring and changed it but it seems to be the same as before.

One thing to consider is for sure to give the bike a proper clean as its dirty as hell.

But I don't think this will solve the problem, sadly.

My gf rides it every day for like 2 hours thought tough terrain.

It got 6900 km in like 2,5 years.

Every 3000 km I have to change some major parts it seems like.

But this time the chain keeps sliping even after the change.

The bike is a Raymon HardRay E-Nine 6.0 - 500 Wh - 2021 - 29 inch/zoll.

Any help is appreciated. Thanks


  • 1
    Any chance the rear mech clutch isn't turned on? But kind of sounds like the hub is not disengaging properly causing the wheel to continue spinning the cassette & chain which would cause all sorts of oddities. Does it happen when you spin the cranks with the back wheel off the ground?
    – Hursey
    Jan 26, 2023 at 22:28
  • "slides off when not pedalling" So if you're coasting along with the feet not turning, then the chain ends up on the inside of the chainring resting on the BB housing?
    – Criggie
    Jan 26, 2023 at 23:53
  • Look, I've been guilty of neglecting bike care myself at times, but... this is disgusting, frankly. Not just the frame, also: what's this white goo on the chain? I hope it's mostly wet lube and not something worse, but at any rate it's way too much of it. Chain lube should only form a thin film, never a layer of visible thickness. Sticky stuff on the chain causes trouble, which can very well include chain coming off. Jan 28, 2023 at 0:42
  • @leftaroundabout 2 hours of moutain biking every day thought the forest that is. The white goo is chain wax, I always used normal lube. But every like 3000 km something is dead already like the chain ring or the cassette so I asked a bike shop owner and he recommended it and said put loads on it. I thought I give it a try. Just cleaned the bike. Haven't had time to test the bike yet. My gf tries to ruin another bike in the meanwhile hers is not working. :D.
    – Schwenk
    Feb 3, 2023 at 16:53

2 Answers 2


Did you trim the new chain to length? Can't see the derailleur in your photo, but if there are too many links then the derailleur won't be able to tension the chain sufficiently.

Chains are almost always sold "too long" for regular bikes. If you still have the old chain you can hang both from a nail, and aim for the same number of links in the new chain.

The links in the old chain will effectively be longer, so don't go off overall length, you must count the links.

  • Even tho it was exactly the same chain, it was to long somehow. I shorten the chain by 2 chain links and everything works as smooth as before. I still can't wrap my head around it but it does its job. Thank
    – Schwenk
    Feb 7, 2023 at 12:38
  • 1
    @Schwenk great work! Yeah the "same length" is not the same as "same number of links" because as the chain wears, each pivot wears on the inside and the chain elongates. So comparing the old and new chains side-by-side the total length of the old chain is longer, but each link is longer. You need the same number of links in the new chain as the old chain has. Its subtle but does make a difference. Excellent work solving the problem.
    – Criggie
    Feb 7, 2023 at 18:32

If it's a new chain, new chainring exactly the same as the old one, and the problem is the chain is falling or sliding off in front when the bike hits bumps or seemingly randomly, the next thing to look at is whether the rear derailleur is properly tensioning the chain. If there's excess friction on the cage pivot due to being dirty, then thoroughly cleaning it and re-lubricating can help (some of them let you take the RD apart to do so, but I don't think the stock one is likely to have this). Or, if the cage pivot area is damaged, that can cause the tension spring to not be able to work properly.

If inadequate chain tension is the problem, then getting a compatible clutch RD like RD-M5120-SGS would likely solve it completely.

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