When deadlifting, if you can break the barbell off the floor just fine but struggle mid-shin, the problem is likely weak quads. That portion of the movement includes a lot of leg extension, and weak quads will obviously be a problem.

There are a few ways to strengthen this weak point, including fronts squats, leg presses, and squatting from starting at a 90-100 degree knee angle. But here's a favorite of mine:

Partial Deadlift (Floor to Knees)

1. Stand on a slightly elevated surface so that the bar starts about half an inch from the floor.
2. Pull the bar to the knees only.
3. Perform this movement slowly to keep the tension on the target muscles.