Fred-
I agree with you.  As an avid user of nearly all types of trails in ANC I don't feel that we need more mtn. biking trails (and those are the ones I use most).  What I don't want to see is further fragmentation of our municipal parks' open lands.  This degrades the experience for the users as well as the wildlife who are forced into ever smaller safe zones, thus increasing the likelihood of human encounters.  I feel like I already have an amazing choice of trails to choose from whenever I go biking - nothing is gained by building more but character (and safety) is certainly lost if we continue to bisect remaining open tracts of lands.