Gear Ratios, whats it all about?
Do you know the correct gear ratios for your bike, put simply a gear ratio is the amount of times one gear must turn for one complete turn of another. Think of your front and read sprocket as gears that are connected by a chain. Low gear ratios allow you to accelerate quickly but have a low top speed whilst a high gear ration has a slower acceleration but a faster top speed.
Lets look at an example based on a speed of 100 KM hr for a gear ratio at a constant rev.
Higher gear ratios need more clutch, which is definitely a consideration when doing single track and uphill work. If your bike isn't geared correctly then its possible to burn your clutch out.
The stuff above is just an example but does highlight what gear ratios can do for your bike and its rideability. It gives you an indication of how your bike will perform with different size front and rear sprockets. Now you can go to your local dealer and argue gearing selections.