Hi bike people In netherlands near the city maastricht and near the belgium border you will find 3 cave systems. WARNING: before you ride fast there you have to check the track. Sometimes ther are 3m deep gaps and holes inside. Unsecure image, only https images allowed: http://www.uer.ca/locations/viewgal.asp?picid=152358 Here is a riding video in "ternaaien beneden" . Headlamp is an old lupine Wilma 5 (16Watt modell) using the newest Lupine upgrade kit.