I think having knowledge of the geometry of bikes you ride (seat tube angle, headtube angle, fork rake, trail, top tube length, BB drop, wheelbase and chainstay length, etc.) and how you think the bikes fit your body and riding style are a big help when looking at new bike purchases. You get a good sense of what works for you and what doesn't, and can use that information to narrow your search.
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- Stan
my bikes
Science doesn't care what you believe.