I was in a hilly 192-mile ultra race back in the old days of freewheels. Well, we were at about mile 120 when my "free"wheel froze, compelling me to ride the rest of the way pedaling, no matter what. That doesn’t sound like much but, when you’re used to coasting down hills and in packs, that extra energy adds up!
Still won it, though - first and only thing I ever got an outright first place in!