So I just bought a Fuji Feather, I think from around 2014? and the gear ratio is 46-16. I'm living in Brooklyn where it's moderately flat but still with a decent amount of hills. 46-16 is nice for the hills but I find myself spinning out for sure downhill and occasionally on flats too. I decided on a single speed because my older bike, an old Raleigh, I used as a single speed because the gearing was messed up and the ratio I used was 51-17 which made me think maybe 46-15 would be better for me. Yesterday I went to my LBS and talked to one of the employees and he said it was a bad idea to go to a 15 in the back because it was fragile? or would brake? He recommended I up the front but I couldn't tell if it was a sales pitch because he followed by telling me how much they could do it for. So the question is, would going down to 15 help me to take advantage of the flats/ downhill or am I really just missing gears?
Also, didn't know if this was part of the issue in any way but I am just under 6'1'' and riding a 61cm frame which feels okay but I recognize it's almost too large...