I have a Dahon Mariner D7, I think about 2015. It has a 7 speed Shimano Tourney derailleur. About a year after I got it I was blowing rear spokes a couple a week. The shop I bought it from replaced the rear wheel with a double rimmed model which solved that problem. Also seems to have put me in a position to easily replace the rear cassette, as there is a spacer in there and looks to be a good amount of room. I'm looking at a Tiagra 11-34 cassette with a matching derailleur and click shifter. That takes care of the back. The front is another story. I don't want to put on a front derailleur, as this bike gets ridden hard and put away wet. The larger gear on the back will give me some more climbing help, which would be nice for those days when I have to walk the bike up the hill from the train station. I want to replace the crank, BB, and chain ring. If I go to a smaller chain ring I can get a little more help going uphill. But I wouldn't mind a little more speed when I'm sprinting across midtown Manhattan to make the above mentioned train. Which would dictate a larger chain ring. I've been punching numbers into Sheldon Brown's gear calculator, and the problem is that I'm just not sure how big a difference there is from 34.2 to 34.9 t0 36.9 in terms of ride.
Any insights would be appreciated.
Anthony