Changes

The road will take you to the A48, which leads to the M4 going East. Plenty of people in that part of Cardiff will be going this way to get onto the motorway.

Alternatively, it may make more sense just to take a bus to the Cardiff Gate Services. In Sept. 2015, we hitched using the option above, waited about an hour, and then just got a ride to the services. Turned up to be very helpful as we got a ride all the way up to Oxford, BUT, there is a bus that runs right there. Take the X59 to Malthouse Avenue, BP Petrol Station, Pontprennau. Not sure the fare but don't think it's much more than the bus that runs to Penylan.