I'd also suggest Tai Wai to Tai Mei Tuk/Plover Cove. It's virtually flat and away from traffic so it's suitable for those without much cycling experience IF you avoid weekends peak time. The afternoons are insane and quite dangerous with people cycling and talking on the phone, stopping and weaving everywhere, going too fast for their ability level etc... More dangerous than being on the road in my opinion. I've never ridden there at that time without seeing crashes. The bike path on the Ma On Shan side is a little quieter and Sai Sha rd to Sai Kung isn't bad either.