After reaching my longest distance of 11.5 miles last fall, and keeping on my trainer few x a week all winter, I went out on Sat and went my furthest ever at 15 miles! The wind form the East, which my bike path seldom gets, definitely helped. I felt it in my leg muscles a bit but no too bad because I went out the very next day and did the same 15 again! As for how long it took..... lets just say if I stay out any longer I will need to find public restrooms!
I really concentrated on keeping my neck, shoulders, arms relaxed, and it did seem to help a bit with my numb fingers/carpal tunnel symptoms. I think it also resulted in a too-slouched back, so now I will try to keep a straighter back. Seems my seat height is perfect, seat fore/aft probably ok, seat tilt I am still trying to tweak. If I can be pretty comfortable like this I will slowly get the handlebars tilt out and down since I have such an urge to lean forward and lower. I think I even might finally love my mini toe clips.
Tonight after work I will go about 9m - I don't think I have enough time to try the 15 again!