Old Backs and Strength Training Exercises

what exercises, and loads, would be sufficient for 1) building bone density and 2) developing muscle recruitment for cycling, other than barbell squats and dead lifts ?

Sorry if I haven’t been specific enough @RobertK.
I am also interested in what exercises build bone density. Is it only strength training? Or can weight bearing endurance activity also stimulate this?
I feel this is relevant to your original question.

Also, as you say, do squats with light weights add to that signalling?