Bicycle performance is a very good read for experienced as well as novice bicyclists or those aspiring to be bicyclists.
It's great to know that a 'bicycle' is the most efficient self-powered means of transportation, and in terms of the ratio of cargo weight a bicycle can carry to total weight, it is the most efficient means of cargo transportation. Folks who live in North America and Europe will be amazed how bicycles are used in developing countries not only for commuter transport but also for cargo transport as well.
A performance on a bicycle would usually depend on the ability of the rider, which means, a strong rider on a conventional bicycle may be able to ride faster than another rider on a racing bicycle. However, if two riders are created equal the rider on the lighter bicycle with a better aerodynamic position will have a very distinct advantage. Of course, if performance is considered "speed" then the gearing (mechanical advantage) will be advantageous. However, there are other considerations too, terrain.
It is simple as Simon to state that you can easily carry a lighter load on a flat surface or uphill. Going uphill with a heavier bicycle requires more effort (huff-puff). If you can roll (like a bicycle wheel does) a heavier bicycle wins with increased momentum which rolls you down faster. So the question of weight vs. power is a bit woolly here I think. Most bicycle travels will have some uphill, flats and downhill so the mass x velocity theory may tells us that with hills and slopes the advantages of light vs. heavier bicycles may cancel out on speed performance, but definitely not on a measured time-trial on a set course - the lighter bike will be the clear winner. In addition, what we now learn is that aerodynamic position is more important than weight as wind drag can really slow a rider down.
When it comes to performance of the every-day rider (one who is bicycling for the joy of cycling or for health and fitness considerations) you can base your bicycle performance on your goals - the MPH you average each week, or on the pounds shed off from bicycling. There would be no need to pay extra money (by the thousands) to get a lighter bicycle that weighs a few pounds less, unless you are a professional cyclist aiming to get the best timing on a race.
But there is something else more spectacular about bicycling. Bicycling takes you to the paths and trails in your backyard, just not far from home. These backyard riding places may be a surprise waiting for you. If you enjoy the beauty of nature and the open country, which some of you may have seen in your overseas travels, you may just not realize that you may find the same or better of it, right there in your backyard. So bicycle performance does not necessarily mean speed, it can also mean how you are performing on a bicycle, like using it for health and recreation, commuting, or touring your neighborhood. If you live in an apartment or small house and do not have space to park a bicycle, then you may want to seriously consider a folding bicycle.