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Bike disc brakes have been in news for allegedly causing injuries to riders in crashes. So to demonstrate how sharp and dangerous they are, I stop a spinning disc brake rotor with my bare hand. Even though this disc brake is on a mountain bike, the disc brakes on road bikes aren’t much different. However the chainrings are like saw blades of death and far more likely to cause injury than the disk brake rotors.

People have commented that the chain is usually covering the chainring teeth. But in crashes, the chain often falls off. Also comments about the chainrings not spinning during a crash. They don’t need to be spinning to cause serious injury. Notice, they were barely turning when they sliced the orange.
They have also commented that the rotor was not hot. The injuries allegedly from disc rotors are cuts and gashes, not burns.