Originally Posted by
WhyFi
AL has rear Iso, not front.
edit: in doing more looking, it seems as if Trek recently changed and is no longer doing rear Iso on the AL Domane. Funny thing is that they're not really doing front Iso, either, at least not in the sense of the traditional Front IsoSpeed with the upper headset bearings in a cradle that allows the front steerer to flex. From the info that I can find on their new "IsoSpeed Fork," it appears as if it's not really doing anything different than any other carbon fork that's allowed to flex a bit, It looks as if it's "IsoSpeed" in name, only.
Respectfully, the aluminum model has front ISO only, not rear. I own an AL 3, same frame and fork as the AL 5. Carbon version has front and rear ISO.
To the OP: you can't go wrong with the AL model. I have no aspirations to race and usually average 12mph biking. I am happy with my AL Domane and would feel confident in recommending it to a fellow rider. Comfortable for 10 mile or 100 mile days. Though I don't doubt a carbon bike would ride nicely as well.
Do let us know what you go with. And pictures, of course.