recently bought a middle ring 32 t M590 from merlin as the old one was getting hooked. I’ve often noticed that deore rings tend to have comparatively small and pointed teeth some of which appear slightly shark finned even from new.
anyhow …also fitted a new shimano 9sp chain and cassette. All seemed Ok for a few rides with the factory greased chain but when I applied chain lube ( squirt dry lube ) and went out the chain kept slipping on the middle ring when under any hard pedalling force .
I returned home and changed the ring for an slx which has larger teeth ( wider and less pointed ) and all is now OK
WTF is going on here and anyone know of a particular model of 9sp deore ring or other that is highly durable ( steel?) with good sized teeth.

Did you fit the ‘new’ ring the right way round?

The small pointy teeth allow the chain to move across to other chainrings.

No idea what is causing your problem

yes …even went and checked which side of the teeth were worn just in case.

Ive been using steel deore middle rings for singlespeed for years, so doubt it’s a specific problem with deore causing your slipping.

Did you line up the ‘tit’ on the ring with the crank arm?

“tit” was aligned correctly!
never had this problem before and can’t fathom what’s causing it .Oh well never mind! It is true though that most of the deore middle chainrings seem to have smaller and more pointed teeth than slx for example.

[video]http://www.youtube.com/watch?v=XcxKIJTb3Hg[/video]