He says things can change in a single kilometre with rough weather conditions.
Stage three is only 48 kilometres and will take the peloton from Riverton to Tuatapere, while the 100 kilometre fourth stage will then finish in Te Anau.
Share the Road rider Jeremy Yates says the first of today's two stages can cause some havoc.
He says on paper it's easy, but if the cross breeze does it's job, some riders could see themselves in trouble.
The Crown Range stage is tomorrow after the two flat stages today.