Originally Posted by joewein

It could be:

1) lack of training: As you build up your leg muscles, more of your weight will end up resting on your legs and less on your rear end, so it gets better with time.

2) the wrong kind of saddle: An overly soft saddle may feel more comfortable initially, but allows your sit bones to sink in too deeply, meaning instead of the sit bones carrying the weight, the soft tissue around them will end up getting squeezed. Not good for nerves and circulation.

3) too much sitting at one stretch: Get up from the saddle every now and then and cycle standing for a little bit, to help your circulation. Take short breaks every now and then.

I really like my Brooks leather saddle. Since I got that, the least comfortable part of cycling were the shoulder straps of my back pack when I was wearing one long distance, sitting was no longer a problem.

Originally Posted by chasm54

Either you need a different saddle, or your position on the bike is an issue. Very difficult to advise, but sometimes small changes in saddle position - nose up, nose down (rarely) further forward, further back, fractionally lower - can make huge differences in comfort. But only make one small change at a time, or you will lose track.

Consulting a bike fitter about position might also be an option to consider.