The worst I've had is a pinch flat on the front while captaining a tandem. Fortunately my stoker was a very experienced rider who didn't panic. We carefully slowed from about 23 mph to change it. It was a club ride so I just let the guys take over. I've changed enough tubes on my own that it does not hurt my pride to let them do it if they want!

Plus it gave me time to let my heart stop racing. Stopping 280 pounds is hard work!

On my single I think the worst was a front puncture that I got just before descending a hill. The bike felt a little squirrelly and the handling was off, but not dangerously so.

Practice changing your tubes at home, both front and rear, with the tools you carry on your bike. You'll feel more confident when you have to do it for real.

V.