Look guys..here is the thing with quads. Those guys who run the 100 yard in 10 seconds have way more blood vessels then the fat guy who squats 10,0000lbs. Quads are NOT for everybody.Only you know if quads are good for you. I have seen guys pin the quad and when the pin got in the pin sat and vibrated and the muscle trembled.Some spurt blood every single time and some pip every single time. So my advice on pinning quads is this...if it is good for you then you will know it right away. You will love it.Painless and easy. If it is bad for you then you will also know right away. You will bleed,you will hurt putting the gear in...maybe all the way down yor leg, and you may hurt the next day.
IF you are going to do quads then sit comfortably with your leg relaxed. Find then end of your quad by the knee and then move to the belly. This is your best spot. If the pin goes in and you feel your muscle shaking then just stop.If the pin is in and the gear hurts your leg going in then stop.