Lanovran

Turns out now that trek is out of 2014 fx 7.4 for this seasson

You may want to have them double-check, because I just looked at the inventory (I work at a Trek dealer myself), and they have plenty of 20" 7.4 FX bikes in stock; however, they're only available in the metallic "sepia" color (no more in black). Granted, I'm in the US, so I suppose that supply lines and stock availability could well be different for Canadian dealers, but I don't know for sure.

I don't mind the small frame, in fact i think (after testing the 7.3 and the 7.2 in medium size) that i prefer a small frame as it feels safer (my feet can reach the grounds while i am on the bike).

Make sure that you have the correct frame size, because that will affect how often and for how long you maintain your desire to actually ride said bike. An incorrectly sized bike will not be as comfortable or efficient as one of the proper size, and with the FX line, size does matter! There's quite a bit of difference from one size to the next on those. The right size bike will be easier for you to control, and will therefore be the safer choice.

As has already been stated here, as well, if your feet are flat on the ground while you're astride the saddle, then your saddle is set way too low. You should need to slide forward off of the saddle to stand on the ground, just as you should have proper leg extension while you're pedaling along. It might seem odd at first if you're not used to it, but it's worth having it correctly adjusted.

1 - what are the implications of moving from shemano acera on the fx 7.4 to the sora ? would that make climbing hill any harder/eaiser ? or maybe the top speed ? should i even worry about this ?

The 7.4 and 7.5 are a bit like apples and oranges. The FX bikes are split into three categories: casual/recreational, daily use/commuting, and sport/fitness. The 7.0 and 7.1 are entry-level bikes meant for casual riders on a budget who aren't looking for quite as much from their bike. The 7.2-7.4 are lighter weight bikes with better componentry, lighter forks on the 3 and 4, lighter wheels on the 3 and 4, and some additional features that would be more efficient and comfortable on longer rides, over greater distances, and with heavier use. The 7.5-7.7, meanwhile, are basically flat-handlebar road bikes, with road bike style gearing, wheels, and such, plus the IsoZone monostay for rear vibration damping. The latter are designed more for being speedy, sporty fitness rides.

2- Is the 7.5 a less versatille bike than the 7.4 ?

Again, the 7.4 is more designed for commuting, perhaps light touring, etc. The 7.5 is geared primarily towards picking up speed and getting a workout without getting drop handlebars involved. They're both quite versatile, but if you have any substantial hills to climb, or if you plan to carry much of a load on your bike, then I'd go with the 7.4.

3 - How wide of a tire can the 7.5 fit ?

The 7.5 has road bike wheels, albeit with more hybrid-like tire clearance. I probably wouldn't try anything wider than 28, but 32 might be doable.

4 - Any other comment on the difference between the two ?

What's your riding style? Is your riding typically more sport-oriented, or more utilitarian? If it's the former, the 7.5 could be a good fit. If it's the latter, I might recommend the 7.4 instead. They're both great bikes, both can support racks and fenders, both are warranted and will last a long time. Above all else, though, I definitely recommend making sure that you get the correct frame size.

On a final note, the new "2015" versions of the FX bikes are just starting to become available, and they have some cool new features. So far, only the new women's 7.3 and 7.4, and the 7.2 disc are showing up, but the rest of the FX family could potentially be coming out in upgraded forms before too long.