I ride between 8 Mile Plains and Shailer Park regularly....
From Cornubia I ride up Bryants Rd, turn Right into Belbora Rd (the intersection out the front of the Spar) then 2nd Left in to Feluga St, up to the roundabout then turn Right into Mandew, around past the back of the Hyperdome, through the roundabout and turn Right at the Nutrimetics building, follow Mungaree Drive all the way to the intersection at Shailer Rd (avoid the bike path at all coasts...too much rubbish and glass and a there's a manic magpie during July and August...actually avoid all the bike paths in Logan!)
Turn Left into Shailer Rd, follow it all the way through the roundabout where the road changes into Winnetts Rd, which is a bit narrow with the roadworks going on with the new interchange, go straight through and down to the other side and turn Right into Village Dr then Left into Brentwood Drive, Left into Chatswood Rd, straight through the 3 roundabouts which takes you on to Rochedale Rd/Service Rd.
Follow that all the way to the Springwood Bus station and turn Left on to Logan Rd (go under the Freeway) and follow Logan Rd up all the way to where the V1 meets just before the Logan Rd on-ramp at 8 Mile Plains.
When the extenstion is finally open you could use that to avoid the Padstow/Logan Rd intersection, the hill up from the Glen isn't too bad!
Sorry but I don't have Garmin map to share of that route...only one where I crossed the highway at the Loganlea overpass, where all the roads works are happening, and rode up the western side (it was a Public Holiday and early!) until the roadworks for the service road between Loganlea/Paradise Rd section are complete I'd avoid due to the narrowness of the road and volume of traffic!
You can go up Daisy Hill Road to get to Chatswood Road...depends on the time of day though...if you're riding through there between 7.30 to 8.30am you'll be battling the school mums driving their darlings to JPC
Hope that helps, Logan Rd for the most part has a good wide shoulder, there's some glass and rubbish in places, and a few idiot drivers, but I'm female rider and I've ridden it alone a couple of times, early am, and many times with another rider at busier times.
There are some good rides south through to the coast and east out to Redland Bay...and West Mt Cotton Rd if you're up for a hill climb!