I will add one more little tidbit... When you are spinning along in your lowest gear, try standing up and SHIFTING one to two gears higher. You can usually do that, as you can throw your weight into the pedals. Go for 50- pedal strokes then sit down and downshift to the lowest gear, and it will feel a lot 'easier' than it did before. Mix it up. Go 50 standing, then 50 sitting, shifting as I've stated. That's when you're on the geared bike...
on the fixie..., well, momentum is your friend, so you want to hit the bottom of the hill hard, then try and maintain... also, sit/stand--but you don't have the benefit of the easier gear when you sit. However, with practice, you find that climbing a hill with a fixed gear is actually easier and more efficient that riding it geared.
train safe-