So my friend has this commuter bike, with a cx 4 motor, i changed the cassette and chain but now the chain has broken twice ..
The chain has broken, both we she clutch on and off….Should it be on? –

Rear mech clutch? I leave mine on.

If she has the single click changer then thats fine but full power, full load uphill changes on small sprockets are the chain destroyers. get her to ease off on the gear changes to reduce the load a bit before applying the power again.

And spend a bit more on chains or an e-specific one, they are a bit stronger.

clutch on or off makes no difference on breaking chains.

As per rickmerister – changing gear under load breaks chains, so assuming the new chain is correctly joined in the first place, tell her to stop changing gear under load.

The only time I broke the chain on my Scott e-Genius was after bending the frame so the rear triangle was at an angle to the chainwheel. I guess this exacerbated the chain line issues mentioned above. Other than that, no issues in 6 years. Try a different chain make/model?

When you changed the chain and cassette did you check the chainring? They are often worn out as well.

A lot of people shift under load, on an E bike it is easy to bend the cassette or snap the chain. A lot of people dont know they need to back of to change gear.

As above I’d more likely blame suspect the user, than the kit, especially on an e-bike… go see how she rides it…
Clutch on btw.

How did you join the chain?

I’m still amazed the number of people who just push the normal pins in and out, when it’s not really been a thing for the thick end of 20 years…

One of the guys at my lbs has ridden my ebike twice.
The chain has snapped, immediately after he’s ridden it.
Twice.
He’s had the piss ripped for showing zero mechanical sympathy. More than twice 😂😂.
Clutch always on btw.

There’s an art to shifting on an eeb as there is on a neeb.
Because you get that ever so slight ‘run on’ of power, you need to unweight a bit more accurately as you shift. More accuratelyerer than you would on a neeb.

Skills course obvs… 😉

nice guys … good advice…. I will talk to her about being more gentle when shifting…

Never snapped a chain sorry. Maybe letting up on the power when changing gear.

World Class Accident wrote

my Scott e-Genius

I’ve also one of them(920). Can I ask if you’ve ever changed the headset ?. I dont like the weird one that came  on it.

I have a 1st gen Shimano 6000steps equipped ebike – it’s really quite laggy for ramping down the power once you stop pedalling and requires a conscious effort when shifting gear.