Final answer:
Repeated trauma to the same spot on the leg can weaken or rupture blood vessels, potentially leading to decreased blood flow to the foot.
Step-by-step explanation:
When you fall off your bike and your leg starts bleeding at the same spot every time, it may cause damage to the blood vessels in that area. The blood vessels can become weakened or even ruptured due to the repeated trauma. This can lead to a decrease in blood flow to the foot if the blood vessels are weakened and cannot efficiently supply oxygen and nutrients to the tissues in the foot.