Let's put it this way... squats, deadlifts, and overhead presses are some of the most basic exercises that all target a big chunk of muscular real estate. Skipping them means you're left using less-than-optimal exercises to achieve your goals.
Your best bet is to make the exercises work for you and either figure out which for tweaks/techniques work best for you or figure out which variations of those basic exercises you can handle.
Check this article for some general tall guy training advice:
Bike riding is not an ideal way to build your legs. The range of motion is too short, so you're doing more harm than good in the long term, and even though you're using "resistance", you're not building actual strength.
Keep working on the basics, but experiment with unilateral leg work (lunges, step-ups, Bulgarian split squats) and dumbbells and machines for upper body work.
Most likely a combination of both. you need to build strength and improve your technique. Nothing wrong with that, since it's where most people are.