When I started cycling again as an adult, I started off with a triathlon bike, apart from stationary bike workouts. I haven’t had any real issues with the saddle. I guess it’s a typical racing/triathlon saddle. You can and should put your weight on the sit bones on a road/tri saddle. Hamstring and lower back flexibility make it easier. Core workouts help too. You also put more of your weight on the handlebars, which is different from the upright riding position of a hybrid bike.
For longer rides, I try to shift my position from time to time. Sometimes I’ll sit a bit off-center, so that I’m almost “sitting” on one of my thighs, not on my seat. Even if I’m trying to hold an aggressive riding position, I will sit up now and then to stretch my back and legs. Just moving around can help during longer rides. Shifting hand position helps to relieve pressure on the hands and shoulders.
Last winter, I switched up and did a lot of riding on the upright, Capital Bikeshare bikes. I found some aspects of the upright position more comfortable, but some were less comfortable. One problem is that all of the weight was going onto the sit bones, instead of being balanced between the seat and my arms/hands.
When I switched back to the triathlon bike in the late spring, I had to go through a brief re-adjustment period. Any change in riding position will put stress on different parts of your body. It will also require slightly different pedaling movements, with a different emphasis on the quads/hamstrings. So any change will require a brief adjustment period, whether you’re going from upright to forward position, or vice versa. At least that has been my experience.
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