I rode a 2 day, 133 mile charity ride with over 11000' of climbing on a fixed gear in May(day one 83 miles 8000', day two 50 miles 3250'). What truly impressed me was the determination of some of the less athletic riders on hybrids or heavy 20 year old mtb's, who maybe ride once a week on a regular basis, and just kept pedaling until the end.
If you can gear up a bit (bigger chainring and or smaller cog) that might make your life a little easier.
If you can gear up a bit (bigger chainring and or smaller cog) that might make your life a little easier.