So I will be attending Michigan State this fall. Michigan State's campus is extremely large so I will be in need of a bike. I really wanted to get something nicer than the average Walmart brand. I have been searching for the past few weeks and the white Windsor Dover 1.0 really caught my eye. I am about 5'10" and the size chart puts me with an 18" bike. The problem is I can't find the bike in my size anywhere. So I guess my question is how much difference is there between an 18" and 20"? Would you advise against me getting a 20"? If so, do you have any other bike suggestions? Any advice would be greatly appreciated!

Thanks,
AJ