Originally Posted by repechage

I have a seat of the pants test before measuring things.
There is a nice straight descent near my house, ride a section no hands. If the bike drifts and or shimmys ( pretty often upon purchase)
I then check the system. there are so many variables, and riders are very adaptive to out of whack bikes.
Rear triangles off to one side are up there.
Wheels that are not in-line are probably the most common.
Then forks.
Fortunately twists in the frame are not common. I avoid frames that have endured a frontal impact, almost always a bit of twist.