Grinding sound from bike

[Artmuzz]

I am having the occasional problem on my Carrera Crossfire-e. Sometimes there is an continuous grinding sound coming from the crank set, chain, cassette when I am out cycling. The sound usually happens when I change gear. What could this be? Please advise.

 

[anotherkiwi]

Chain rubbing would be my guess.

 

[Deleted member 4366]

Are you sure it's not coming from the motor? Just to makes sure, check that the connector near the motor is fully together.

 

[Brynric]

I had this noise earlier today. It was intermittent and wasn't there yesterday.
I dropped into a Halfords to see if it was a known fault. Apparently not but a thorough spray of lubricant seemed to do the trick. 20 miles on and I haven't heard it again.