Right now I ride without clipless pedals. I don't know the exact terminology of the thigh-muscles group, so I'll refer to them as front thigh muscles and back-thigh muscles. I feel like the front-thigh muscles are getting stronger than the back-thigh muscles. Is this normal? If I get clipless pedals (and use them correctly) will it start improving my back-thigh muscles as well or do I need to do additional gym training (like when you lay on your front, have weights attached to your feet, then you curl you feet back above your back-thighs, thus developing the back-thigh muscles)?