hey all, thanks a lot for the replies! apologies for the late delay in reply, as a lot has happened in the past month. shaunbee - thanks for the pic of the tyrell chainring guard. it looks similar to the chainguard that is on the mu sl though, maybe the dimensions are different which makes it work.
I agree with Shaunbee and jur's comments regarding the movement during a gear change - i can see the "jump" moving along the chain just before it reaches the chainwheel, and cause the chain to jump out of the chain guide.
I did try holding off pedaling while shifting, but is still able to reproduce the problem, although it is less common. So for now, i just stop using the chain guide. No chain drops, and more importantly, if the chain does jump and drop, i can just put it back on without unscrewing the chain guide.
thor - do you have a link on that sharkteeth chainring? i understand your comments about not being able to sell them, but if you can post a link, at least i know what to lookout for.
jur, havm66z - what is this driveline you are referring to?