overnight train and bicycle transport

See this page, on the most comprehensive Website about train travel, The Man in Seat 61:
http://www.seat61.com/bike-by-train.htm#.UR6XzdV1GSo
(In particular, the last section called "Travelers' Reports at the bottom of the page has a first-hand account of Romania.)

Also, do some googling and you will find some pages like this:
http://www.warmshowers.org/content/how-travel-train-and-bike-romania

Also, there is an On Your Bike thread here on the Thorn Tree.

Trains are fairly dependable but delays can and do happen. It doesn't appear there is an overnight train from Bucharest to Sibiu -- it's only about a 5 hour trip. All train schedules in Europe can be found at www.bahn.de (search for Bucharest as "Bucuresti")

Thanks for the links, but I won't be looking for international bike transport of railway companies, just national ones.
It looks like the Romanians love to get their bribes from Western tourists. I'm inclined to find out it what happens if I refuse to pay any extra fee.

According to the public railways' operator (CFR) rules you can take bikes:

• on long distance trains (InterRegio) if they have cars with "a lot of internal space" (this mostly refers to double-decker cars but obviously leaves ample room for interpretation/bribery) or if they have special cars with storage space for bikes (with a 10 lei fee);

• on all commuter trains (Regio), just in 2nd class cars (though most Regio trains only have 2nd class) and with a 5 lei fee;

The overnight train from Bucharest to Sighetu Marmatiei (Maramures) runs part of the route as an InterRegio then as a Regio. You will almost certainly have have to bribe someone to take the bike aboard.

Out of the two direct trains from Bucharest to Sibiu (at 10.00 and 15.30), the one leaving at 10.00 usually has special cars with storage space for bikes

It looks like the Romanians love to get their bribes from Western tourists

Ticket inspectors like to get bribes from anyone, including Romanians (who naturally make up the largest share of passengers). As a result the railway company is practically bankrupt.

I'm inclined to find out it what happens if I refuse to pay any extra fee.

At best you'll get an endless argument with the ticket inspector, at worst a fine for oversize luggage (250 to 400 lei/€57 to €92).

Before reaching Sibiu's train station you can have have a nice stay in Bucharest at the Trianon Hotel! Good value for money! We stayed there this winter!

There have been a lot of steps to eliminating bribery on Romanian trains. You might find the staff will want to follow the rules no matter what. However if a conductor doesn't want your bike on the train you can at least try offering a bit of cash. Bucharest to Sighet in Maramures is a long journey and you will want to be sure where your bike is while you are asleep. If packing your bike compactly and putting it on the shelf over your head is possible you might look at that. I will try to contact a Romanian friend who might know the current situation. You might want to post on the On Your Bike branch.

Romanian trains are still very slow and delays are really common. If heading for a flight I would leave plenty of hours to spare.

Edited by: MrRipio