How tight do you have your chain?
I've read a lot of NS riders talk about having the chain like a banjo string surely that'll just wreck the bearings.
Are NS just as prone to tight spots as OS bikes?
I've set a bike up and low and behold there's a tight spot on the chain, everything is new, it's a new bike and I just swapped the cranks. I know what is causing the tight spot, the chainring is not spinning true, just a few mm out but enough to cause a tight spot.