How do you know if....

[The Anabolic Avenger]

....a 1 inch pin isn't long enough for quads and you need to go to an inch and a half?

 

[HUCKLEBERRY FINNaplex]

You should feel slight 'discomfort' as it enters the muscle.If your bodyfat isn't outragiously high,then a 1" should be sufficient to reach the muscle of the quad.