Normal? Probably yes. Solvable? For many people, yes. On a regular upright bike, your fitness has much to do with how long you can stay comfortable. As long as your energy remains high, much weight is supported by your feet, not hands and seat. The right shoes, right fit, and frequent rides all go a long way. Those frequent rides should be well within your 'comfort' zone. The special occasion long rides will probably still come with some discomfort. Weekend warriors mostly have to be content with short rides.