Commuting bike Both and never needed either for MY bike in 5 years. My one flat in that time happened while the bike was sitting in my foyer almost 2 hours after getting home. Tube just blew and scared the hell out of my wife and I. Thought a water line went in the Laundry room. I have patched a few tubes for others while out.

on My hot rod road bike for Sunday rides I have had one flat and their was no fixing it. The tire actually split causing the tube to blow. Had to call the SAG (wife in the mini van).

The way I look at it on the commuter is I'd rather have it and not need it especially if on my way to work when it happens. Ten minutes of riding is about 40 minutes of walking/carrying a bike. Takes about 10 minutes to change a tube. 15-20 to patch.