So, as I recently posted, I took my Birdy to a local dealer/shop in Germany and got it upgraded etc.

I forgot to ask him what other mods he would suggest, so let me beg the indulgence of folks on the board.

I am head back to NYC where I have a several mile commute with some moderate hills. Is it better to keep the existing 11 or 12 tooth crank that I have (birdy's have no front derailleur) or should I up it?

What mods will improve my ride (as opposed to appeal to my desire to have cool components etc.).

Looking for practical suggestions - I'm not a person that shys away from spending money for quality, but I am pragmatic.

Thanks in advance for any suggestions.