I don't think there is a small loop. Best you can do is a T shaped ride starting from Santa Clara and riding the various expressways to get to a start in either direction depending on what you want to tackle first. Adding the back side of Mt. Hamilton down to the Isabel Creek bridge and back up again will lead to a nice lactic acid session. The grade is steeper the whole way back up with few sections to recover. Full exposure to the sun as well. How many miles are you thinking?