Wish I could understand being into this - it's like watching golf to me. I just don't get the fascination.
I can understand how someone who is watching a cycling event for their first time might not appreciate the sport per se. But the TDF is akin to watching the 24 Hours of Le Mans vs. just watching a standard automobile race that might last 2 hours.
At some point there has to be an appreciation of the endurance aspects.
Additionally...the main commentator duo of this event (Phil Liggett and Paul Sherwin) do an amazing job of explaining and describing the historical references of the various parts of Europe the tour visits as the event moves forward. Discussion includes geography of the land itself and history behind many of the villages, town, cities, and their associated landmarks. The fact alone that this event is held in Europe provides a wonderful opportunity and backdrop for this type of commentary. We are truly looking at the "Old World" and it's very intriguing for those who appreciate the aspects of history and heritage.
There is also a long history of this event and with that brings a long history of the participants. The riders. They come from all over the world and many have been competing in the TDF for many years. They represent their country as well as the team they ride for. These cyclists are among the most fit of any athletes in the world. Which is another aspect that creates interest in this event...the marvel and admiration one has for both mental and physical attributes necessary to compete at this level of sport.
I could go on and on but those are a few reasons this event is unlike any other sporting event and why I appreciate it so much.
I also feel it's a bit of an acquired taste. Most fans have been watching for years...and the more you watch the better it gets...IMHO.