There are three core routes into town from the Playford Council Area. Main North Road is the central route. To the west lie Salisbury Highway and Highway One. On the east side is Bridge Road – Hampstead Road, or the option to jump the range to the range and come in along the River Torrens – North East Road corridor. There is also the option of taking the Stuart O'Grady and the Northern Connector Bike paths, which are further to the west again, but then you end up in Port Adelaide!
Salisbury Highway equals Main North Road for flatness, and the bike lanes are generally better, although they disappear periodically. Like Main North Road, it is fast, especially with a following breeze. I've never had stuff thrown at me, and the lanes are generally clean of glass and rubbish.
The main problem is that the end of the highway leaves a cyclist with about 3 kilometres of no-bike-lane Highway One down to Gepps Cross. And, being high traffic, it's very noisy. Nonetheless, you could go this way, although I have never taken the full route. I have frequently used sections of Salisbury Highway to get into Mawson Lakes, especially coming from the South. As well as my city commute, I have a weekly trip to Kurralta Park, which usually involves passing through Mawson Lakes in some capacity.
The section in red (Highway One) has no bike lane, last time I looked. (May 2021)