Dismounting also enables you to turn your bicycle into an effective weapon. I was once attacked by an aggressive and determined big dog and had to ram him repeatedly with the front wheel before he got the message and gave up savaging the tire. My father was a livelong quail hunter, so I grew up with dogs, having bred and raised hundreds in my lifetime. Most dogs can sense the absence of fear (the same as sensing fear itself) in someone and tend to tone down their aggression.