I would like to have a little bit of a lower 1st gear and little bit of a higher 7th gear but I like the spread of the gears that I have. Rather than messing up the cassette is it possible to install a front derailler and have 2 gears - or even 3? I don't need 3 at this point but I am working now on putting a motor (chain driven on the rear) and if I do I may very well need a higher high gear - the third ring may be desirable. I know that they sell clamp on deraillers but I think I would have to make the crank wider - maybe as much as 1/2 to 3/4". Is this possible? Is it possible to add a 3 speed hub gear on the rear and get it to work with the 7 speed cassette - creating 21 speeds? It seems like this would be a lot less messy and would not interfere so much with folding the bike or the chain line.
What r the limits?