Like-minded people (and other stuff):
Online tutorial:
Oliscout, the Bike Guide around Trier and in the Eifel:
The international initiative for mountainbiking
The german initiative for mountainbiking
Site for mountainbiking in Luxembourg:
https://sites.google.com/site/bikerluenglish/
The national lobbying group for cycling in general:
The link about cycling and mountainbiking in Luxembourg from the National Tourist Office (ONT):
http://www.visitluxembourg.com/en/what-to-do/nature-tours/cycling-routes-and-mountain-bike-routes
Through this link, you can download all marked hiking and cycling tracks in Luxembourg:
http://tourisme.geoportail.lu/?lang=en
Open Street Map for Luxembourg:
http://www.freizeitkarte-osm.de/garmin/de/luxemburg.html
Mountain-biking in the Ardennes:
http://www.ardennes-lux.lu/index.php?page=sport&id=2663&lan=fr&lieu=&types=
Some good guys doing a lot for mtbiking (MTB club in the Müllerthal):
Hotels in Luxembourg that offer some facilities (like luggage transport) for cyclists in general:
Public transport in Luxembourg (cycles are accepted, generally for free):
Luxembourg's national cycle route network:
http://www.pch.public.lu/fr/pistes-cyclables/index.html
Sports and science (in relation to cycling)
http://sportsscientists.com/cycling/
My favorite bike shop in Luxembourg (Rédange/Attert and Lux.-city):
Singletrail grading by difficulties:
http://www.singletrail-skala.de/overview
The best reference I could find on the net on first aid
http://85.25.34.248/bergmed/bergmed.php?section=5
A quite complete reference on what you would have to pack into your backpack for your transalp
http://www.mountainbike-transalp.at/index_125_125__1000000433_1_0__.html
Two refernces for mountainbiking in the very nice Saarland:
Wild animals / plants in the "Grande Région"
Mountain-bike rental in Luxembourg
Test bikes by S-cape in Rédange (Specialized)
Tour operators abroad
Links to sites from people I know or where I got positive feedback from friends that took part in their events:
https://www.mtb-fahrtwind.de/de/mountainbike-reisen/home.html
http://www.trailxperience.com/
http://www.bergfuehlung.de/programm/mtb
Marc Vaisse's MTB school (in the french Alpes de haute Provence)
http://www.wix.com/maclemak/ecole-vtt-blanche#!
The weather in Luxembourg
http://www.wetter.com/wetter_aktuell/wettervorhersage/7_tagesvorhersage/?id=LU0LU0006
http://www.ana.public.lu/fr/meteo/previsions/index.html (French)
Safer cycling
http://www.thebikestoragecompany.co.uk/bike-safety-guide/
http://www.rospa.com/road-safety/advice/pedal-cyclists/sharing-the-road-together-drivers-cyclists/
In case you like it wild and rough