Stainbank's not a great place to try build up your endurance as the trails are quite short. That said, as Red pointed out it's a beautiful little reserve with quite a bit of fairly tame wildlife which makes for a really enjoyable ride. That coupled with the reasonable entrance fee (R15), accessibility and some great little stretches of singletrack makes it one of my favourite spots in Durban especially if my time is limited and I just want a quick ride. As regards safety, there have been a few incidents there, especially at the bottom near the river. Apparently however the guys were caught and there hasn't been anything for about a year now. I still probably wouldn't suggest riding alone though.