The Bafang is geared down considerably and will pull the hills just fine. Get an aftermarket Liekie Bling Ring 42 tooth and forget about your problems. If you want to have better gearing for no power use then go with 11-46 or so in the rear. The minimum number of teeth on the chainring for a good chain line is 42 unless you purchase some expensive stuff. Then you can get down to 40.. The stock chain ring is okay on a bike path but not mountain biking. .