Internal Cables

[Sluicehoops]

What is the advantage of internal cables over external ones?
Is it purely for aero-dynamics? If so, does it really make much difference on a road bike?
Or is there another reason for them?

Thanks.

 

[ianrauk]

Aesthetics. Frames do look really nice without cables all over the place.

 

[Smokin Joe]

Makes the frame easier to clean.

 

[raleighnut]

Saves from cables catching on objects or yourself.