For my last test ride, I wore a t-shirt and skirt with my bike shorts underneath. We had other errands to run that day, and I didn't want to be stuck in lycra all day. Once I had decided what I wanted to ride, I shucked the skirt and put on my cycling shoes. I think the shop guy was pretty surprised. He didn't say anything, but he kinda had this look on his face like, "Oh good, she really IS serious about this...." I think he was wondering how it was gonna work out with me testing a road bike in short skirt and flipflops.

I'd just repeat what others have said, be comfy, but it really does help to test ride in at least the bottoms and shoes you would normally ride in.

good luck - and have fun! (I loved bike shopping - though making the final decision was a little stressful)

Christy