Dirty Workout, you knees should not hurtdoing fronts, check your form again.....you still need to sit back as in a back squat and although the hamstrings ar recruited to a lesser degree, they are still keep tight and flexed throughout........Stingrays are okay if your goals are bodybuilding related, but for the strength athlete, I personally feel they have no place in the program......and this is why.....you can't use them to clean!!! This is what is bothering me Shades, and I am trying to help, not jump all over you......you said you are cleaning, you rack the clean in the same manner as the front squat, and yet you are only having problems with the fronts......this is like an alarm to me that something is wrong with your form on cleans......just check out some videos and pictures of cleans and front squats, then practice with just bar, stretch the forearms out good, and practice a nice, firm rack....it is okay if you don't utilize all of your fingers, just keep your elbows high and rest the bar on the shoulders and you shouldn't need a stingray.