Helpful phrases
All Terrain Biking or simply ATB: MTB in English!
Links
Check out 

www.mtbroutes.nl for trails in all of Netherlands. Other Dutch links that may prove useful are www.singletracks.nl and www.mountainbike.nl.
Books
A book that could be of interest is the ANWB Routegids Mountainbike Nederland (the trail of Bergschenhoek has been given the rate 4 out of 5 as to difficulty).
Personal notes
and place I am planning to go to
. For anyone with a hesitant feeling for geography, the numbers correspond to the numbers on the map ...
Friesland (1)
Groningen (2)
Drenthe (3)
North Holland (4) (nl. Noord-Holland):


Spaarnwoude, Texel, Wieringerwerf
Flevoland (5)
Overijssel (6)


Enschede(Zuid), Hardenberg, Hellendoorn, Holten, Lemele, 
Oldenzaal, Staphorst, Steenwijk, Stegeren, Vasse, Zwolle
South Holland (7) (nl. Zuid-Holland):


Bergschenhoek, Leiden, Noordwijk, 

Oostvoorne, Rijswijk, Zoetermeer
Utrecht (8)

Lage Vuursche, Leersum, Nieuwegein, Soest, Veenendaal, Zeist
Gelderland (9)

Hoenderloogroep, Lochem, Nijmegen, Oosterbeek, Rheden, Wijchen, Winterswijk, Zeddam
Zeeland (10)
(11) (nl. Noord-Brabant):

Bergen-op-Zoom, Best, Bladel, Den-Dungen, Deurne, 

Dorst, Drunen, Eersel, Gemert, Gemonde, Liempde, Lierop, Liessel, Luyksgestel, Mierlo, Nuenen, Oirschot, Overloon, Reek, Reusel, Roosendaal, Schijndel, Sint-Oedenrode, Soerendonk, Someren, Valkenswaard, Veldhoven-Vessem, Vlierden, Waalre
Limburg (12)