Chain jumping in 4th gear

[ebikeerwidnes]

Hi all
I have a problem with my bike and I need some advise
WHen I am riding in 4th gear - which is my normal cruising gear - it sometimes 'jumps'
it feels like the chiain missed a cog somewhere or somthing - accompanied by a loud click - and the pedals jump forward a fraction

It used to be rare - a few times in a 20 mile ride - but a few days ago it got to the point where I can no longer ride in 4th with any pressure on the pedals at all - it just jumps constantly - a few times every pedal rev - but then stops for a short while before starting agiain

It can't be a dud link on the chain because
a) it only happens in one gear and
b) it happnes far more frequently than a single rev of the whole chain


I have been through a lot of muddly puddles recently and I though it might be mud jammed in the gear cogs - but I have cleaned them and it doesn't seem to have helped


Any clues would be welcome!!


Thanks

 

[Ming the Merciless]

How many miles have you done with that chain and cassette? Is the chain worn or relevant cassette cog worn as the symptoms you describe after often a point to replace if you don’t measure your chain for elongation.

 

[Cycleops]

New cassette and chain, problem solved. Clue, it’s happening in your most used ‘normal cruising gear’.

 

[Ajax Bay]

Aligned with the unkind one above, and @Cycleops , your chain skating on the sprocket you use most is the classic result of an elongated chain which has now worn the cassette to beyond end-of-life. This is on your e-bike , right, so because you have a spare 250w on tap I bet you don't bother changing gears much either. A normal rider will use a variety of sprockets; but not you (mostly).
Procure a new cassette and chain. In the meantime avoid riding on the fourth sprocket (and you'll be fine).

 

[ebikeerwidnes]

Aligned with the unkind one above, and @Cycleops , your chain skating on the sprocket you use most is the classic result of an elongated chain which has now worn the cassette to beyond end-of-life. This is on your e-bike , right, so because you have a spare 250w on tap I bet you don't bother changing gears much either. A normal rider will use a variety of sprockets; but not you (mostly).
Procure a new cassette and chain. In the meantime avoid riding on the fourth sprocket (and you'll be fine).

Yes - this is my ebike - currently on 3500+ miles over 1 year
in terms of riding style - I tend to try to keep my pedal revs about the same so I probably change gear more than many ebike people - but I do agree that it may be a wear and tear problem
LBS had a good look over the bike in November becasue I wanted it checked before any parts of the guarantee ran out - I asked him to check for wear on gears and chain etc and he didn't report any problems - but I may go back and talk to him about this specific problem

Thanks to all for the answers - very helpful

 

[Ajax Bay]

You've done very well to get that mileage (ETA: google "e-bike chain wear" for more) - probably because you change gears more than most. A mechanic will not be able to tell whether the cassette is worn to end-of-life by inspection. And even if she'd taken it for a ride, in November the cassette, wearing in happy concert with the chain, would've been fine. You can go and talk to her, if you like, to find out what cassette and chain you need (fitted (or to fit yourself)). In the meantime, it'd probably be safer to avoid using the auxiliary motor assistance , certainly in fourth gear.