Sure, Altair-
The train left at about 3pm and arrived at Chambord at 12:45 am. I just walked the bike down a little dead end and cowboy camped in a field. If I were doing it again, I would call
Bernard Renauld, 418 580 0109 or 418-900-3535. He is renovating Auberge de la Gare in Chambord and might have room. A very nice and hospitable guy, say hello from me.
Coming back the train stopped in Chambord at 11:38pm and arrived in Montreal at 10:00am. The station is not open, but you can make the reservation by phone and they will send you alerts about the train being late, etc. The train had a baggage car. In Montreal, I checked the bike and each pannier separately, and they handed them down from the train in Chambord. Heading back, I handed the items up, no platform, and the conductor ladies brought me the baggage claims. In cooler weather the schedule changes to run during the day, I don't really understand why. Montreal station is very nice with a wide array of restaurants among which to choose.
Bon Voyage!