Trek Pilot wsd vs 1600 wsd

[KSH]

I agree the 2.1 is the best bike, but it is not 'full carbon'. I believe that it is aluminum with carbon seat stays and fork.

I got confused....

Frame ZR 9000 Alloy w/TCT Carbon seat stays
Fork Bontrager Satellite Plus, carbon

Alloy is...metal?

But it does have more carbon.

[Triskeliongirl]

ZR9000 is an aluminum alloy, a very high grade one at that. Read more here:
http://www.kleinbikes.com/us/road_bikes/index.html

For some reason trek doesn't define it but Klein does. But, some very high end bikes are combinations of high grade aluminum alloys and carbon (like the cannondale six13). A bike that is 100% aluminum can be too stiff (i.e. good power transfer but not comfortable) while some bikes that are 100% carbon cannot be stiff enough (i.e. too cushy, weaker power transfer). I am only now learning about tube stiffness, as I just got a new bike that is reynolds 853 steel. This bike is definitely stiffer than my titanium bike, and even though it weighs more I think it is actually faster since the power transfer is more effecient. BUt getting back to the posters question, your post with the specs makes it clear which is the better bike and why. I would say unless the pilot geometry does not suit her body or riding style she is best off with the 2.1. She will outgrow a tiagra bike really fast, but shimano 105 is really solid and will take her quite far (and of course the ultegra bits are a bonus). The carbon seat stays will insure she is comfy enough to keep riding.

Another comment, shimano105-10spd is a much better group than the 9spd 105/tiagra bontrager mix. It was completely redesigned last year and is excellent. If you really get into it, as parts wear out they will be interchangeable with ultegra10 if you want to upgrade, but you can't upgrade from 9 to 10 spd piecemeale, you need to change out a lot at once. SO, *if it fits you* pilot 2.1 is the way to go. BUt, make sure on the fit. I personally can't ride treks cuz the seat tube angles are too steep for my long femurs. But if I could really like the pilots.