I've had my Trek 700+ for 10 months and have just over 2,000 miles on it. I keep the assist in the lowest level 95% of the time. Riding in Western Oregon, I usually have a few hills. My typical rides are 30-40 miles, but I've done some that were in the 60-70 mile range. Anytime I do more than 50 miles I worry a bit, but so far I've not used up the charge.