That was Eugene Christophe, who was leading the overall classification when he broke his fork and had to run down the mountain with his bike on his shoulder to get to the blacksmith. He wasn't disqualified, though - he was just assessed a ten minute penalty on top of the two hours he'd already lost.
The story so compelled France that a collection was taken up for him, and he ended up with quite a bit more money than the eventual winner of the race did. And I can just about guarantee that some of the SS/FG bikes ridden by forum members have chrome steel toe clips emblazoned with Christophe's name - they're still available today.