Most mountain roads go up and stop, so you have to cycle down the way you came up (albeit much faster). However, the Rokko road runs along the ridge line (people often speak of the "Rokko sanmyaku" or Rokko mountains). Therefore, you can tackle it from either side (or from the north, which is higher in elevation and therefore cuts the climb by a couple hundred meters or so). Here we assume you want to start from the population and transit centers of Kobe or Nishinomiya (midway between Kobe and Osaka). We also assume that you want to go east to west to get virtually all the climbing over with at the beginning - from that point on, it's almost all downhill apart from a couple of steep but short uphills getting over the ridge to central Kobe. Access to the start of the road up is available from the Hankyu or JR lines; Hankyu Shukugawa is the easiest, but JR Nishinomiya is not far away (about 2 km to the east). Note that there are also two cable cars that reportedly allow bagged bikes - taking one of these will get you all the way up to the 900 meter level, changing the ride from Herculean to Hardly Worth Mentioning.