Hi all, I'm in the process of gradually modifying a 21 speed entry-level hybrid into a practical commuter and I need some advice on swapping out the current forks and derailleurs.
The current forks have the impressive title of 'Mozo C-51 suspension fork' but they don't actually do anything but go in and out and make 'pffft pffft' noises. I figure this is a waste of energy so I want to swap them for a rigid fork. Question is, what measurements do I need to know so that the new one fits and doesn't affect the steering geometry in a negative way? Ditto any special tools that might be required to make the change?
The derailleurs are Shimano Tourney (i.e. bottom of the barrel) with Altus/Acera Ci- Deck Plus V-brake/shifters and while they work ok when they are adjusted properly, they don't stay in adjustment for very long. The spring on the rear derailleur is also a problem as it is far too strong. I would like to swap the current front and rear derailleurs for a better Shimano product (possibly Deore) while leaving the shifters alone. Is this possible or is the current cable pull too long/short?
Finally, and this is a curiosity thing, does anyone know what the unused nozzle/hole is for on the shifters? It looks like it might take a cable attachment but on my bike it doesn't do anything.
Thanks in advance for any and all help.

