Over-estimating my chances

Yesterday was upper body day at the gym. I decided to ride my bike, and to try to negative split the ride back. I knew that would be daunting, because the ride back is slightly more uphill. But nonetheless that was plan.
I made the ride there in just over 10 minutes, never pressing too hard. Then I did the workout itself, which was relatively easy (I might need to increase the weight in some things next time). Then it was time for the return trip.
Things were going great until I made the first turn: a sharp wind from the southwest was hitting me right in the kisser, and it kept up pretty much the entire ride back. So the return trip was more like 11 minutes, and it was 11 TOUGH minutes. My calves were burning when I got off the bike.

I'll bike to the gym again today, but since it's lower-body day, I don't think a negative split is too likely.