Why are Bicycle Saddles
so narrow and hard?
Bicycle saddles are much harder and narrower than you might expect because they are designed to bear (some of) your wieght on a small area, primarily the ischial tuberosities , a.k.a the 'sit bones' which are protuberances of the pelvic bone that you can feel as solid bumps if you feel under your buttocks as you sit in a chair. As explained in the FIT section, as you are pedaling, your weight is divided between your sit bones, your feet and your hands.
If you sit on a larger area, for instance on a soft cushion, you will be sitting on muscles and associated buttock tissues. This does not even work for soft car seats, which cause your legs to fall asleep on long rides. On a bicycle, a wide, soft seat carries your weight on the muscles that pedal the bicycle. Although this may be comfortable when you sit still on the bike in the show room, after any time pedaling, the pressure causes a "charlie horse" in these muscles for lack of adequate blood circulation. You will want to avoid such soft saddles if you plan to ride more than a few hundred yards, because riding will become painful.
Ride a conventional firm saddle, daily, until the area over your sit bones is no longer sensitive. Along with all other bicyclists who ride substantial distances (mare than 100 miles/day) adapt to such saddles, none of which have the broad, deep cushion often sought by newcomers.
Even an experienced rider who is laid up or otherwise cannot ride for more than a month, experiences the same temporary discomfort as any new rider when he or she returns to riding.
The big cushioned saddles are made for people who don't ride bicycles. That is why there are so few of them available, and we generally advise against them.