Heat the oven to 425°F and coat a wire rack set over a sheet pan with the canola oil.
Whisk the buttermilk, mustard and salt in a large bowl and turn the drumsticks through it.
Combine the crushed chips, flour, onion powder and pepper in a shallow pan.
Shake excess buttermilk from each drumstick and press on the chip mixture until evenly crusted.
Arrange the drumsticks on the rack without touching and bake for 20 minutes.
Turn each drumstick carefully and bake for 20 to 25 minutes more until crisp and at least 165°F beside the bone.
Rest on the rack for 8 minutes before serving.