Originally Posted by
TurbineBlade
I think tightening in the "star" pattern is just good practice more than anything else. It probably doesn't hurt to just go in a circle, but I can imagine that doing it the correct way probably keeps the chainring "flat" against the spider a bit better during installation, and keeps you from having to re-tighten each bolt as much.
Maybe the rings are less likely to become imbalanced on the spider and loosen? I don't know.
As I understand it, car wheels are self-centered onto the hubs by the conical lug nuts (or bolts if you drive a number of European makes). If you tighten one nut too much before the others, it will impede this self-centering action as the wheel is essentially locked into one position by that one tight nut. Similarly, if you tighten one side before another (like when you don't employ the star pattern), the wheel may also not center properly.
None of this self-centering stuff applies to chainrings since they're not centered by a conical fastener but by the position of the chainring bolt holes on the crank. Your chainring bolts either fit, or they do not fit. The clamping force of each chainring bolt is localized to that bolt and the only thing to worry about is whether it's tight enough.