Matatus run frequently from Nairobi's Accra Road stage (near the old Tea Room stage off Tom Mboya Street) to Nyeri. The journey takes about three hours along a tarmac road that climbs steadily out of the Athi plains and into the highlands. From Nakuru, Nanyuki, and Nyahururu there are also direct matatu and bus connections.
There is no scheduled passenger rail to Nyeri. If you are driving, the A2 highway north from Nairobi is in reasonable condition; allow a little longer in rain.