Yes, it's been some time since the last bike induced injury.
My bike is a mountain bike. Those have spiked pedals. These provide a good grip when my feet are muddy and wet. They also scratch my shins every time I decide to push the bike forward with my shins, but that's not too bad (and after all, I could use my hands like everyone else).
It takes some real talent at being clumsy, but I can also propel them backwards into my heel, powered by nearly my whole weight.
That leaves a nice wound.
Positive aspects: Heels don't bleed very much. Having to continue biking immediately helps to distract you.
Negative aspects: OUCH!
Good thing I do not believe in omens, otherwise I'd not even bother with today's exam.