The verktyg cut a slot method is very safe. If the corrosion is real bad cut two slots. Cutting aluminum has a completely different feel from cutting steel. When the saw touches frame metal you know it. The frame doesn't even get scratched, more like a polish mark. Need not take more than 15 minutes. Use a thin hacksaw blade, not some fat thing. Hacksaw blade can be held with fingers, no special handle necessary. First time takes longer from excess of caution. Will not work with super long MTB posts deep inside frames.