So I live in Houston/Katy/Cinco Ranch area and I work at a Papa Johns in Missouri City which is 25 miles of a journey for 5 days a week. I didn't have alot of money when I bought my bike, and I needed a folder for whenever I get a lift at any random time and because I love small wheels. I bought it on amazon for 129 dollars and its a pt062 Jane folding bike, really low quality bike but I've been slowly replacing many objects on the bike from the loose cup and cone bottom bracket to the chainring and the changing my 14-28t freewheel to DNP's 11t to 32t freewheel.

Bike weighs between 30-35 pounds, my current chainring is 48t and rear cog is 13t. I can ride the bike at a constant speed of 18-21 mph if there is no wind, if the bike was half its weight I could ride it much faster. I get to work in about 1 hr 30 mins for the 25 mile journey.

I really want to make the bike faster but for some reason I ride my 13t rear cog faster than my 11t I can max out the 13t to 24 mph but the 11t I struggle to stay at 20 mph.

What is everyone's fastest average speed along with their chainring size and most used rear cog?