New to cycle, recommend a bike for under $400.

[MyNameIsRequires]

Hello y’all, new to cycling and was wondering what bikes would you recommend for under $400? I’ve been using my cousins bike (geared) and my friends and I have been doing 20+ miles on this bike path. It’s a flat surface with only 1 hills that is not steep. The bike could be single/fixed or even gears. All are welcome, thanks!

I was wondering the Retrospec Harper single gear because it’s cheap and around my price range but I don’t know if they are good ride for 20+ miles.

 

[Cycleops]

Hello and to the forum.

I guess you’re in the US. The Harper might be okay, it looks like a typical made down to a price bike from the Far East. Here’s a link so others can comment:
https://retrospec.com/products/harper-ss
The supplied tyres will have poor puncture resistance so unless you enjoy mending punctures you’ll need to swap them out pretty soon.
For what you have to spend you might be better off with a secondhand bike off Craigslist or from a yard sale. We’re mostly brits on here but we have quite a few members from over the pond, perhaps @Gravity Aided could give an opinion.

 

[Gravity Aided]

American fixie and S/S bikes like this are much of a muchness, I think ordering some wheels, a crankset, and buying an old ten-speed with slotted rear drop-outs will do the same job, but better. I always suggest bicycle co-ops for this. There always seems to be a guy who does conversions like this hanging around, plenty of old steel frames, and the expertise to get things set up right. That falls well within budget parameters and provides for some local relationship and advice. That being said, the retrospec bicycle is cheap for a fixie at this time, in this market, where there are few, if any, bicycles on store shelves. I'd want to make darned good and sure the bike can handle your local terrain. I live on the prairie in Central Illinois, so it's not a problem. I have shifters, sometimes I even use them.