Identify the Type of Fallacy in the Following Passage

Short Answer

Identify the type of fallacy in the following passage.
first bicycle rider:How come when we coast downhill you always go so much faster than I?
second bicycle rider:Because I'm heavier.Heavier things fall faster.
third bicycle rider:Wait a minute.I thought that was what Galileo proved wrong.
second bicycle rider:C'mon! That's only common sense.Heavy things are bound to fall faster.Just look at how fast I coast-and I'm the heaviest.