I know that feeling!!! Where you get out riding and are thinking to yourself - "damn, did I really gain that much weight?" "This is way harder than I remember - am I THAT out of shape???" Then you inspect your bike and see that the rear brake is off center and slowing you down. Ooops.

I did this on a group ride with a bunch of people I only partly knew. It was our first time having been invited to ride with them. I felt so badly for holding everyone back as I brought up the rear!! After the mid-ride break when I discovered the break issue - no one could understand why I was all of a sudden super strong. I didn't want to admit to my mistake, so I said that I must have been running on empty earlier and a little snack made all the difference!