I just booked my seat on the TGV to catch the TDF Time Trial on July 23, 2005 in St. Etienne. There were no 1st class seats but some 2nd class seats for:
7/23/2005
Paris-St. Etienne (depart 7am arrive 9:41am)
Catch almost all the TT in St. Etienne (cyclist departures 10:40am-4:40pm)
St. Etienne-Paris (depart 6:12pm arrive 9:01pm)
The tours have probably grabbed up the 1st class seats. It looks like you can still get the 2nd class. I used the RailEurope.com site. There are probably others.
You'll be back in Paris for dinner and the TDF finish the next day.
