I just changed the chainring on my bike, for the first time. I've got sugino rd cranks. The rear wheel seems like it's aligned, but if I press my finger on the sidewall of the rim slightly whlile I spin the wheel, I can feel slight variations in pressure agains my finger, so I'm sure the alignment isn't "perfect." Also, I never really checked my bike before (and I didn't set it up), but now I see that the chain is tighter at some crank positions than others. At some points it almost seems tight, and at some points almost loose. Is this all normal? Is there any special way to make sure everything is aligned as good as possible? Also, is the variation in the chain tightness possibly related to the bottom bracket or the cranks? I understand that better cranks, for example, are made to closer tolerances. Maybe the chain ring also?