Ciao faifaifai38,
You're right, it is hard to find information in English about how to get to Abetone, the top ski destination in Tuscany. It is hard to also find info in Italian for that matter, but then once I found which bus line you need to take, the details are easy.
From Florence to Pistoia:
Coming from Florence, the best option is to take the train to Pistoia. Most trains take 35-40 minutes to get to Pistoia. You can see train schedules at:
trenitalia.com
From Pistoia to Abetone and back:
Once in Pistoia, leave the station and cross the Piazza Alighieri in front of the station to get to the right bus. You want to take bus #54 - take a look at this map since it shows where bus 54 stops at (area C):
http://www.copitspa.it/DATIPDF/fermateStazione.pdf . The buses are marked COPIT/BluBus.
Here is the bus timetable for #54:
http://www.blubus.it/Invernale/IQ_54.pdf
It is only in Italian, so let me help you decipher it.
A few only reach San Marcello, others continue all the way to Abetone. For some, there might be a bus change in San Marcello, that is hard to understand from here. The hours with SC at the top of the column run only on school days. The times in bold run even if there were to be a strike on that day. At the very top, the times "arrivi da Firenze" marks the time the train arrives from Florence, indicating that you have time between then and to get your ticket and get on the bus (if you didn't get it in Florence). The first two pages show times for weekdays (feriale), the third page shows times for Sundays and holidays (festivi).
Fares and tickets:
The bus is an "Extraurbane", which literally means it is a bus that leaves the "urban" area of Pistoia. Bus fares vary according to km you travel. Many buses in the region and the country function by "ranges" of km you mean to travel. From the timetable, you can see that from Pistoia to Abetone you travel 51.9km. At this time, the info on the bus website indicates that for this amount of km, you fall into the AC fare which is € 4,20 for each one-way ticket.
In Florence, you can buy your tickets at the BlueBus/Lazzi office located right outside the SMN train station -
the number is Pza Stazione 4/6 (map it on Google so you can see where it is, it is to the right of the station if you're facing the front of the station.
If you were to need to get tickets in Pistoia, head for the BluBus/Copit office across the square in front of the station, at the corner (near where you'll catch the bus to Abetone).
Hope you have a wonderful time skiing - do let us know what you think of Abetone and whether the ride up and back is a good way to get there!
