Retrofit ebike - cog misalignment ?

[CPD]

A new to me e-bike has a cyclotricity mid-drive unit fitted and it works well, apart from when I change to the highest 2 gears, when the chain comes off the front (driven) cog (the chain comes off on the inside of the driven front cog). The photo shows the problem well I think and tells me that either the driven (front) cog needs to be moved inward, or the rear cog set needs to be moved outward. Is my thought process correct, and if so, how would I achieve this ?. Many thanks ......

 

[Ajax Bay]

Chain guide ftw.

 

[Jameshow]

Single double or triple chainset, if double or triple then the chain should be on the smaller chainrings when on the larger cogs of the cassette..

 

[Big John]

I've just Googled Cyclotricity mid drive unit and it comes up with a single 42 tooth chainring with a plastic chain guard, which I think matches the photo. As suggested a chain guide might do the trick.

 

[CPD]

I think this photo shows it even better, and yes it is a single 42T with plastic guard. So either the front chain ring has to move inward, or the rear gearset outward, otherwise on changing to a lower gear the lateral movement of the chain would cause it to jump off the front ring, which is exactly what is happening. A chain guide would certainly help but I cant believe they will cope well with this much lateral change in direction. To add insult to injury, the chain snapped when I was out this morning ............................ watch this space

 

[Aristotle Kristatos]

Wack a friction controlled front mech on and use it as an adjustable chain guide.

 

[CPD]

Wack a friction controlled front mech on and use it as an adjustable chain guide.

Hi Aristotle, thanks for your message. Could you clarify your meaning of "friction controlled front mech" ?. Many thanks, Alan

 

[Aristotle Kristatos]

Hi Aristotle, thanks for your message. Could you clarify your meaning of "friction controlled front mech" ?. Many thanks, Alan

Fit a front mech without indexed shifting .