Justin My suggestion that you could ride everyday was based on the total weekly milage which would still not be excessive.If you add in weight training or to give you a break from the routine some days would be appropriate.I do both ai just go by feel ie if I am too tired or don't feel like riding that day I'll rest (or focus on weights).I agree my concern on focusing on one sport cycling included is repetitive overuse of certain muscles and joints and it is a good idea to crosstrain for this reason as well as for the variety you mention.I use weights for my intense training for balanced developement of muscle(and joint/tendon/bone etc.) size and strength.I do the cycling at a lower to moderate intensity primarily for cardiovascular and fatburning benefits(ie at a more sustainable pace) but usually go long distances often staying out all day. Sometimes I will stop at a nature center for a hike or a large mall for a fast walk.But I hate doing aerobics indoors on a stationary machine so just find what works for you.As far as the leg extentions most people do use a full range of motion but stay with relatively light weight and use it as a warmup to pump blood into the area or a finishing/detail movement focusing on the teardrop area late mentioned.If you keep it light it would tend to strengten the area around the knee and with limited stress the knee itself.The key is to not start ego lifting on this one and stop at any sign of pain/strain(keep in mind it is important to distinguish between the good pain of exertion and the pain of overexertion(overtraining)or improper exertion(strain).Of course unless you use a wide leg position it won't hit the inner thigh area.With leg exercises if you take a wide stance (keep toes pointed on same plane as knees)you will shift stress of of the knees and more onto the inner thighs.