I thought they ran big...I got my jersey three years ago, though. I had to exchange a large for a medium, and that still feels relaxed.
Their t-shirts, on the other hand, run very small!
LOVE Twin Six!
ETA: FYI, there isn't elastic/grips on the bottom hem, at least on my jersey (the Betty).
2007 Trek 5000
2009 Jamis Coda
1972 Schwinn Suburban
"I rejoice every time I see a woman ride by on a bike. It gives her a feeling of self-reliance and independence the moment she takes her seat; and away she goes, the picture of untrammelled womanhood."
Susan B. Anthony, 1896