Only if you don;t cut them. Once you start making them narrow you need less and less sweep. MTB flat bars have sweep too anyway it's just less because they are designed to be narrower. Some of the silly flat bars people have probably would do better with a forward sweep.


You should not move your saddle to solve bar placement issues. You will cause more serious problems elsewhere.

I rode 20 miles this past weekend on a fixed gear road bike with moustache bars. This bike has been totally comfortable for me on my daily 5 mile commute. After 15 miles, my butt was sore. Riding fixed really doesn't allow me to get my butt off the saddle every once in a while for a break. My back was a little sore too, but that wasn't because of the fixed gear. That's because I was riding with my wife and we were going kind of slow so my legs weren't really bearing that much weight.

So, I guess I'm proposing you fix your back problem by riding faster. You need to be pulling on the handlebars not leaning on them.