"My bum hurts!" is probably the number one reason women cyclists give up biking. It doesn't help that most people overdo it the first time they get back on the bike after a long break too. Especially those who choose to get back into cycling by doing a 50-mile charity ride with no prior preparation!
For most people, the soreness quickly recedes and after a few more days of riding, getting on a bike is no longer painful. It's a matter of getting your bum used to sitting on a saddle, preferably an anatomic and women specific one, and your back and shoulders used to the new sitting position.
Positioning a Saddle
Of course, there are ways to minimize this initial discomfort. Check your saddle isn't too far forward on the 'seat post' and make sure it's a decent width and supports your sit bones properly. Many men's bikes do not come ready fitted with comfy enough saddles for men let alone address the anatomical differences of women's bottoms.

Inserts, gel and ti rails
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There are many women specific designs available from wide sofa style saddles for upright comfortable riding positions through to race oriented versions that at a glance look like men's race saddles. There are multitudes of saddle in between too, often equipped with gel inserts, springs and cut away sections.
Gel inserts inside and springs underneath the saddle provide much needed comfort and pressure relieve especially for beginners and novice riders, but they do add some element of weight gain to the saddle. The springs let the saddle bounce underneath you when pedaling along (which can lead to a fair amount of bobbing around and, whilst comfortable, isn't very energy efficient). However gels inserts and varying density foam padding can alleviate pressure from certain areas with out much added weight.
To convert your existing saddle into a gel one you could fit a gel-filled saddle cover, Velo from Moore Large do one for £12. Alternatively, fit a sheepskin cover from Easirider, tel: 01604 870713.
Always bear in mind, though, that too squishy a saddle won't be supporting you properly. Over time try to wean yourself onto a harder, more supportive saddle so that you put more of your weight onto the sit bones away from soft tissue areas.
If your saddle is too narrow, all your weight is concentrated towards your pudendum instead of the sit-bones, the ischial tuberosities. In men the sit bones are roughly three inches apart; in women they're four inches apart. This is why women's saddles tend to be wider. On a sit-up-and-beg bike you're taking a lot of your weight on your bum; on mountain bikes and sports bikes a lot more of your weight is shared with your handlebars.

A sporty women's saddle
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Don't fit such a wide saddle, however, that it chafes your thighs, find a happy medium with support and performance in mind.
If, after altering your riding position through trial and error, moving the saddle forward a touch or fitting a wide - possibly sprung - saddle or a suspension seatpost, and you're riding in proper padded cycle shorts, you're still uncomfortable, maybe you might be on the wrong sort of bike altogether? Many of the mountain bikes in the shops are designed for racing and so sling you far forward into an uncomfortable position. Expert riders and racers are used to this position and it's quite comfortable for them but for the rest of us a more 'sit-and-beg' position is desirable. Hybrids are normally more upright and so more comfy for beginners and the comfort bike can be even more upright. But for performance and comfort's sake you don't want to be so upright that hardly any of your weight is supported by the handlebars. Again, aim for a happy medium and seek advice from other women riders and see what your local shop have to say about your set up. A few tweaks can make all the difference when you're uncomfortable on a bike.
We recommend tilting the nose of the saddle down slightly, only a few degrees though, to reduce pressure on the nose and increase contact and weight bearing on the sit bones. This also encourages more weight to be taken with the arms, so make adjustments slowly and in small increments to avoid discomfort or injuries elsewhere. Or try a saddle with cut-away sections, grooves and holes which by the sheer omission of the saddle in places prevents pressure points and chaffing, especially in the pubic area.
Setting saddle position
Height
Saddles set too high or low can lead to knee injuries, so it's crucial to find the right position, you can do this by sitting on your bike and putting your heel on a pedal in its lowest position. The saddle and seatpost are the right height when your leg is straight (but not locked). The seatpost should not be extended above the inscribed safety limit, you should buy a longer seatpost if necessary.
Fore-aft
Most saddles have rails by which they are attached to the seat post clamp, by undoing a locknut or Allen key bolt will enable you to slide the saddle forewards or backwards. With the pedals horizontal to the ground you should be able to draw a vertical line from the front of the forward knee through the centre of the pedal spindle.
Angle of tilt
For true comfort on a bike the tilt of the saddle is crucial but is largely a matter of taste. Women tend to like the saddle nose pointing to the ground slightly, to relieve pressure on the pubic area. That's why women's saddles are shorter than men's. The Terry Liberator saddle gets round this problem by cutting a hole out of the nose.
By making just minor adjustments to the saddle's tilt you can radically improve your comfort. Try your saddle at different angles and ride about for twenty minutes or so to check which angle suits you best.
This article courtesy of www.onyourbike.com