Stronglifts and starting strength are both very good.
As you haven’t got a squat rack you will have to improvise a bit.
Build a routine around, deadlifts, squats, bench press, military press and pullups/rows
You can do front squats if you clean the bar to your chest. http://www.exrx.net/WeightExercises/OlympicLifts/FrontSquat.html
Same goes for military press http://www.exrx.net/WeightExercises/DeltoidAnterior/BBMilitaryPress.html
You will have to do both of these with light weight and higher reps as you cannot rack the bar if you fail. Leave a couple of reps in the tank.
I’d have a good read of stronglifts and learn the form for the major lifts before upping the weight.
The two most important exercises are the deadlift and squat. Depending on your biomechanics you will probably be more suited to one or the other. The deadlift is the number one exercise you can do to help with riding. The squat is arguably the better all round movement as long as you have the mechanics for it.