@BigonaBianchi if you go from a 12-29? ( I can't see one in the shimano 10sp range) to a 11-32 you are increasing the range at the expense of a a closer grouped cassette.
These are the gear inch charts for a 12-28 and a 11-32 on a 50/34 chainset, on 700x25c tyres.
The 12-30 is a much better option as you will get better stepping between the gears
However as
@Big_Dave says the sram 12-32 is probably the way to go if you want a 12-32, I really wouldn't bother with starting at 11th as in most riding it will be a wasted gear only good for speeding down hill on the 50x11 it won't get used on the 34x11 (or shouldn't), even if I could spin a 50x12 at 90rpm its 29mph on the flat, so what you need to be looking for is the closet grouped cassette with the lowest gear.
this is a 12-32 chart
As I may have said on my triple I can get lower than that with a much closer grouped rear cassette on the inner ring, which i can change from 26 to 28 or 30 (but I don't have one in the same size) this is a chart of what I propose when I can afford a 12-23 cassette.
This has a better range high to low and better ratios than shimano's current set up of triples i.e. 50/39/30 this is an example.
As you can see the possibilities are endless, but from my experience, which isn't too great, I would miss the 17th, and I know I hanker after that 18th, it just seems a big jump to me from 17 to 19.
For the record a 26x25 is 27.6" so sacrificing the 19th for the 25th you get the widest possible range with the best set of ratios.
Hope this helps.
My dream would be an 11sp triple 12-25
