You can ride your bike in comfort all day with the right saddle.
Bicycle saddles are available in a variety of shapes and designs...
A bike with an upright cycling position (e.g. hybrid bike or recreational mountain bike) requires a broader saddle.
On a drop-handlebar bike, more of your weight is supported by your arms - so the saddle can be narrow.
The narrower nose of the road bike saddle also prevents chafing of the thighs over long distances.
A gel-filled bicycle saddle can add extra comfort to your ride and elastomers or springs can soften things up a bit for the recreational rider.
A gel bicycle saddle and a pair of padded cycle shorts will keep you comfy for most of the day.
Some bicycle saddles have a groove down the middle - this is intended to relieve pressure 'down there'.
Bicycle Saddles are available in different materials - fabric, plastic or leather covering a stiff chassis. Kevlar edges offer scuff-protection.
The metal bars under the saddle are called the 'saddle rails'.
All saddle rails (except on some BMX/jump-specific saddles) fit a standard bicycle seatpost.
More expensive bike saddles will sport saddle-rails made out of lighter, exotic materials such as titanium or carbon fibre.
The more exotic the material - the more you pay...
Brooks Leather Saddles
Brooks have been manufacturing bicycle saddles since the 1800's and Brooks saddles are still made in the traditional way - just leather. A Brooks saddle enthusiast won't sit on anything else!
Women's Bicycle Saddles
Women's bicycle saddles are available with all of the above features but with some differences...
A women-specific saddle will have a shorter 'nose' and a wider seat area to support the wider female pelvic bones.
If you are riding a bloke's bike - replace the saddle with one designed for women. It will be much more comfortable...