Originally Posted by Cheval vapeur

Thank you for taking the time to answer me. I actually have a bike with shifters of outside derailleur. It's brand new mountain bike and I don't plan to change the cassette. Previously my daily ride consisted of a long flat road heading up a higher but longer hill. I could pick up momentum and around the middle I could slow down a bit and change gears and complete the climb standing up. But I've moved and there's a hill to climb before I get home and I can't gain momentum, it's too short. Several times I tried to shift into low gear on the middle of the hill and my chain came off. My only solution right now is to switch to low gear from the start and all the way through.