There is no way anyone will check if you don't have two hand brakes and are riding fixed (fixed wheel is considered a brake by law) so it's fine. I wouldn't do it brakeless though! There is a condition against having bull horns though. Again as there is 20000 riders I have no idea who the fuck would check/notice/care but still that is a thing worth considering.
As for hills I've ridden those FG/SS and done ok on 44/16, but found it a bit grindy. I'd aim for 68gi ish so you can make it up the hills and then cruise at about 18mph on the flat without problem.
There is no way anyone will check if you don't have two hand brakes and are riding fixed (fixed wheel is considered a brake by law) so it's fine. I wouldn't do it brakeless though! There is a condition against having bull horns though. Again as there is 20000 riders I have no idea who the fuck would check/notice/care but still that is a thing worth considering.
As for hills I've ridden those FG/SS and done ok on 44/16, but found it a bit grindy. I'd aim for 68gi ish so you can make it up the hills and then cruise at about 18mph on the flat without problem.