The thin part of the track is godawful. I lag a bit too much to adjust my steering quickly, and taking a curve on that thin part always throws me off because I can't adjust the steering midway through (either not enough, or too much, and the lag keeps me from getting it right). It dumps me off the cliff. Judging by the comments on the server when I've remarked on it before, I'm definitely not the only one with this issue.
Make sure your tracks are wide enough that those of us who can't steer perfectly can still make it.