Commuting Bike
 

I have a 6 mile ride to work, which is mostly local highway.

I am considering purchasing a Cannondale Synapse 4 Sport Road Bike for my commute. I don't mind wearing a backpack for anything I need to carry (which is not usually much).

Do you think this bike is a good choice, or should I look at something else? I expect to pay $400-$700 for it, used with 400 miles.

Commuting is an adverb , not a pronoun, is it not?

{cue: the English Majors]

ride what you have and see.

try your commute on a day off, and see how it is, time it,
and add some extra time to mend a potential puncture.

Imagine what its like in the winter on it.

what ever winter is like where you [undisclosed] live

I have a Cannondale Synapse 6 that I have been riding lately and I really like it. I mostly ride at the beach so the traffic kinda watches out for cyclist. IMO if you don`t have bike lanes where you are I think I would consider a road bike along the lines of the Synapse so you can cruise kinda fast. I`m still not use to riding in alot of traffic so sometimes I take some backroads in my route. I think I might invest in a mirror. Let us know what you decide on, later.

The most important thing about the bike is the fit. If the bike you are looking at fits and you're happy with the test ride, it should be fine for your commute.

It depends. If the bike fits and you enjoy riding it then go for it. There are a lot of different options for attaching a bag or a rack if you want to carry things.