New chain comes off triple chainrings

[Cymro74]

I have two tourers with triple chainrings where over the years I've noticed new chains sometimes come off the lower chain ring, but not after it is worn in. Neither bike normally has any problems with dropped chains as L screw and cable tension are correct. The dropped chain issue has only happened a few times over the years, but always within a few weeks of a new chain. Seems to happen when moving between first and second chainring when I've changed too late going up a steep hill.
Any suggestions?

 

[Sharky]

Only thing I can think of would be a slightly stiff link where you joined the chain and which sorts itself out as it beds in. You've just been unlucky that the stiff link hits the front just as you try and move the chain across.

How did you join the chain?

 

[Cymro74]

Always used KMC chains with quick links

 

[boydj]

I use a 'dog fang' chain keeper - a simple fitting to stop the chain coming off the small ring.