Originally Posted by
steve_cay
Being a dual sport, you get suspension, wider wheels and tires, more aggressive tire tread, and something closer to a mountain bike geometry!
Personally I'd have phrased it as "right in between" the typical fitness and cross country MTB postures since its equally far removed from either. And this I think is what has made the DS line so contentious when it comes to fitting (at least the 2013/2014s). Its like there is a tipping point where you either need to sit up OR go prone to be balanced.
Funny you mention the X-Cal because just the other day I was plotting its frames (DS on the left, X-Cal on the right, click to enlarge)...
Regrettably I cannot plot the FX because Trek doesn't provide the frame stack/reach figures (which, ironically, are what really matters when comparing postures). Anecdotally though, I would guess the FX's would end up looking similar to the DS, just with a
taller cluster of head tubes pulled in a little (as to whether those taller head tubes raise the bars or simply make up for the shorter legs on the rigid fork....without those reach/stack figures we'll never know).
The obvious take away of this comparison is of course the fact that the xcals reach is longer and stack is lower (the angles and other metrics are more about handling and less about posture/fitting). But the visual also drives home the point that while the DS line offers what appears to be proportional sizing....it does so within a TINY window: literally less than 1" different in reach between the largest and the smallest, and less than 2" in stack! This is why I say that sizing on a DS is
almost moot point: with the exception of stand-over its one step away from being a
one size fits most. The X-Cal on the other hand has more than 4" of reach between the smallest and largest, and about and inch and a half in stack.
Note that while a 21" seat tube (for example) on a DS
really is 21" (yes, I've measured), on the X-Cal they are all 1"
shorter than the quoted bike "size". So on the "17.5" model, the seat tube is actually 16.5 inches (thank you Trek for making things even more convoluted). My
guess is that they do this because some people over the years have gotten hung up on that size naming convention as if bikes were shoes (I've seen people say things like
"In a Trek I take a 17.5").