On a standard bike, there's only three bits of you in contact with the bike - at the pedals, the handlebars, and the saddle. So the first time you ride for a longer distance you might discover something makes you sore.
The good news is that acheiving comfort is often just a case of a few simple adjustments.
You should be placing the ball of your foot over the pedal spindle. Any other positioning is less efficient and can cause you health problems if you continually do it.
The most common mistake is to let your wrists drop. That's why it's becoming more common to see ergonomically-shaped grips on mountain bike handlebars.
And most importantly is the bit we sit on! There is more controversy over what is a good design of saddle than anything else.
Firstly, you should make sure you have it at the correct height. Which is why our buying guide focuses on your leg length when choosing the right size of bike. It's possible to cycle with the saddle set a bit lower than optimum, but not by much, and it definitely shouldn't be set any higher.
Then it's gender and back angle that must be taken into account. New bikes are fitted with a saddle that is suited to the gender of the rider and how far forward they lean to reach the handlebars. So all saddles are not created equal, and these are important factors when buying a replacement.
We see quite a lot of padded covers on saddles, but we're not convinced that they're the right solution because they tend to slip. For longer journeys, it's best to imitate racing cyclists and wear padding inside your clothing. You can buy a basic pair of padded lycra shorts for about £15. And if that's not a fashion statement that you wish to make, then wear a thin pair of normal shorts/trousers over the top of them - the padding in the shorts next to you will still do the job :-)
If any pain persists, then you should see a doctor, but it might help to have read a bit more about it first, in which case we like the Sheldon Brown articles .
We won't comment on medical problems, but our Dr Bike will look over how you fit your bike and advise on any obvious points.