Originally Posted by abdon

Yeah, those are 100% fair points, and that first link is actually pretty darn good.

Forget about the hole for a second as it is proving to be a distraction; have you seen any resource measuring the amount of load a fork experiences along it's length? Interestingly enough steel forks tend to break/bend much higher because while that area has more metal it is also the one experiencing the most stress due to leverage. Well that and at the drop casting but those are due to material defects, too hard/brittle of a casting.

In any event; it may feel to go against logic but drilling a hole on the lower part of the fork, where there is less metal, should also be less of a toll on the overall strength of the fork as this area experience smaller loads. Drilling holes on the upper part of the fork ought to be of more concern.

Chances are I'm not going to do it on this project but I may start chucking dead steel forks in a pile and eventually test these assumptions. Basically rig the forks so I can crush them on both a hydraulic press and under sudden shock, see where they like to break even with a hole on them.