I put a cassette on that matches my abilities for each ride. Takes about 5 minutes. I even do it for training rides. I have a long rear derailleur. I mix and match cogs to come up with 11-21. 12-21, 12-23, 12-25, 12-27, 13-30, 13-32, and 14-34. if you cant maintain 60 RMP on the steep grades then you're under geared.
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Slim