I'm 5'10" and with a rambler rolled up I have vision problems. It's a bit of a stretch with the regular flap as well.

How does it sit on your back? If you're a bit taller, and the Rambler still gives your vision problems, I might as well factor that out.

If you have problems with visibility, wear it lower on your back or loosen up the suspension straps.

There fully loosened. Wearing packs low on you back pulls your weight down and is horrible for you back. Not doing that.

I can see, obviously not as well as without a bag, but I can still tell if a cars coming.

It depends on your riding position and how the pack is loaded.

I use it for school so most of the time I'm on my feet.

I read somewhere that with a more up right position it is better to have the weight higher on your back, and vice versa with a more aero position. When I'm on my bike, it's more comfortable to have it sit lower on my back (like a messenger bag). Sometimes when I get on foot I tighten the straps a bit.

Though to be honest, it usually doesn't bother me enough to fuss with it.

There's usually a perfect middle-ground. Once you know your riding position, it's quite simple.

I find that I adjust it depending on the load and how it's loaded. Any fully-loaded bag is going to give me issues with visibility though. That's something I've just accepted.

Yeah, I said I was 5'7". I don't have visibility issues. I thought I would, but... Then again, I don't care if I have to turn around to see. I have done that riding at 25+ mph, but that was in a lot of traffic and I had to cut across three lanes of traffic and then turn down a street on the left. It really was the best option, since I had to point to various cars to get them to let me over. My wife saw me from a bus and said that I ride way too fast. lol I told her the only way to get across traffic there is to ride as fast as the cars.