Well in theory the fastest bike route is 115km, which probably means the scenic route is about 150km.
I took 4 days to cycle Dordrecht - Eindhoven, following the wind and taking in more distance and scenic towns (such as Heusden, Lieshout, Mariahout and more). If you want to do more distance (Rotterdam is further than Doredrecht) in 1/4th of the time I took, that is up to you but it will be hard work especially if you don't have the best gear, and perhaps headwind all the way. And perhaps rain all day. (I don't know when you plan on doing this.)
Also be aware that apparently the national park called Biesbosch near Dordrecht is under construction and lots of bike paths are closed off, changing every day.
So yeah it's a good idea to check which train stations are along the way and what the options are inbetween Eindhoven and there. Cycling Eindhoven - Tilburg is probably much more realistic for a beginner on a rented simple bike with no special panniers. Beware that the area around Tilburg train station is under construction and you need to walk through a sandy 'field' for a while.
The fastest bike routes (red lettering on white signs) are often alongside smelly motorways and not very inspiring, and can be boring and ugly. The scenic ones (green lettering on white signs) are much nicer, but are detours through forests, heathland, past farms and meadows and cute towns, and more kilometers and take more time. More explanations about scenic signposting systems in that other thread I mentioned in post #5.
50km would be a nice daily distance for a beginner or even for a mellow biker who likes to enjoy scenery and take breaks like me. Eindhoven - Tilburg via scenic routes should be about 50km.
Edited: 7:51 pm, September 14, 2013