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@supertramp
the bb itself is symmetrical. simply, the drive side crank extends further onto the spindle than the left side. which ever side of the bb spindle the crank is placed on.
i don't want to know how to bodge it up or if the chainline 'seems' ok. any chainline which is out is a bad chain line. the problems with a bad chainline are increased wear, loss of power and lack of safety. the safety issue being that when a chain is not tight there is an increased risk of the chain falling off and this risk is greater when the chainline is out. now a few millimetres is not easy to spot with the eye, just measure it with a vernier caliper, every bike shop should have them...
if "90%" of the miche cranks hit the chainstay on a pre cursa frame im wondering why the other 10% does not. do these anomalies arise from the frame or the cranks? or a combination of both being badly designed.
my conclusion is that the cranks were intended this way, for the drive side to extend further on. i believe this was intended to maintain a 42mm chainline. a compromise as to maintain the aesthetic look of the cranks which are relatively straight.
just to conclude this. the pedals should extend equally from the frame.
also for intended safety.. if a chain falls off a bike this means something is wrong, it could just mean you need to tighten it. but when it comes to a fixed gear where your chain is your means of braking its imperative that this is set up properly because if your chainline is out the chance of the chain falling off is increased and more likely to happen when you brake.