Every fitter will have some idea about "how a bike should be ridden." Some might really try to accommodate you .... But I would be surprised if most of them didn't have a "That isn't right" set-up, which they would reject even if a customer wanted it.
If you get the $300 Retul or whoever which does multiple videos with lasers and such to make micro-adjustments in cleat thickness and such .... then at least the cleats should be right.
A Defy might have a longer wheelbase, longer chain stays, and maybe the weight a little further back, on top of a little less head-tube angle. Endurance bikes are Supposed to be "stable" versus "racy" in their handling, I guess so you can take off your jacket and stow it, or get food out of a pocket and eat it, without the bike changing lanes three times.
If you like low and long .... why get a bike which is short and tall?
Here is another issue, IMO:
Originally Posted by
razorjack
coz I wanted to avoid any issues with my knees - i had broken leg some time ago and i need special (asymmetrical) setup,
however no issues with upper body - also this is something easy to setup and experiment yourself - saddle for/aft, stem, handlebar
Moving the saddler fore and after Definitely affects everything about riding position, Especially legs, because it changed the location and thus the angle of your hips while pedaling.
Of course .... I could eb wrong ... . but everything I have Ever heard abo0ut bike fitting is that the first thing you find is where the saddle sits relative to the BB, and relative to where you sit on the saddle. Get the height pretty correct (within a few millimeters) and the saddle position correct (again within a few millimeters) and never change it unless your body changes massively (like severe knee injuries or horrible arthritis or a spinal fusion) because you are putting out all the power you can through your legs and associated joints, and there is usually one "best" orientation for each person depending on each person's proportions and flexibility, where that person can put out the most power with the most comfort..
Sure play with it for a TT bike to use different leg muscles to maximize the run---in effect, sacrifice cycling efficiency in order to max run speed, which is where triathlons tend to be won. And make little adjustments if you take time off from cycling and lose strength and flexibility over the winter or whatever. But pretty much, your legs will always turn a set of pedals with optimal output and endurance in a single orientation, and that should be the basis of fit.
After that, however far forward you like to reach and how ever far down you like to lean, depending again on fitness and flexibility, determines your other contact points.
You can use any variety of stem lengths and angles .... unless you go for a 150-mm tiller or a a direct-mount BMX stem, you should be fine. You can raise or lower the stem with spacers (assuming your steerer is long enough) and you can get bars with different widths, drops, and reaches .... to fine-tune your upper-body position. None of these should dramatically change the handling unless you go with dramatically odd-sized (50-mm or 150-mm stems etc) parts and pieces.
Personally, if I had leg issues and really needed to be careful with my knees, I wouldn't mess with saddle placement if I got it right. But it's easy for me to talk because my legs are pretty much the same length. I assume, I would just get either a different-sized crank if the difference was more than 5 mm and would use spacers under the cleats if it was less.