yea they're definitely bad for your knees. Generally the bar goes over the ankle area and to exert leverage to get the weight up, unnecessary force is imposed on the knees. If you're trying to work quads, yes squats, leg presses are definitely beneficial. I like wide lunges as well. the stepping leg still only drops 90 degrees, but you feel it everywhere, quads, glutes, hams, calves. I havent experienced any knee issues from it and the burn is unreal. you can do body weight, or with the bar or dumbbells. thats pretty much all my leg work outs consist of. I like the basic movements. heavy leg press, heavy squat, 5-6 sets of 25 wide step lunges (depending on the weight, could be less sets), and some deads, and then some calf work. 45-1hr and youre toast.