Joe,
The hard part is knowing (while still in the States) if the train you
want will accept your bike. A general rule: the smaller/more local
the train, the more likely it is to have a designated place for a
bike.
You can get this info from each station's yellow departure
timetable--a bike symbol on the timetable entry indicates that the
train accepts bikes and usually has a car with a designated car. The
blue bike symbol appears on the outside of the car, and the trick is
then making sure you're standing where the bike car stops. This info
is usually shown on a platform display of the composition of each
train.
In Tuscany, trains are surprisingly scarce. For instance, you can't
tour the hill towns by train (of course, we don't want to go by
train--that's why we take our bikes), so it sounds like you'll be more
concerned with long hops between major cities. I have a very detailed
Italian timetable book at home, and I'd be happy to give you the info
therein if you send me an e-mail with departure and arrival dates (and
times, if you can narrow it down) and cities. While it's a couple
years old, most of the info is still applicable, including the
bike-specific info.
You can get timetable info at www.trenitalia.com, but I don't think
there's much bike info there. You can also check raileurope.com or
call them--they might be able to get more detailed info than what's
available online.
Cheers,
Eric
Lawrence, KS