Take your typical winner of the local road race and add that to the winners during the first week of all major Pro Tours and what do they all have in common? They can all sprint, and usually very well. To be a successful road race performer, irrespective of category, a finishing sprint is an invaluable asset.
The most technical aspect of sprinting is tactics...
To some extent, sprinters are born, not made. Genetically, the better sprinters, such as Robbie McEwen or Tom Boonen, will have a predominately higher percentage of type II muscle fibres (white-coloured due to the lack of myoglobin - an oxygen-carrying protein). Type II fibres have the ability to contract rapidly, generate high forces (power), but unfortunately fatigue very quickly. While endurance-based training develops the efficiency of type I fibres (red-coloured due to the larger quantity of myoglobin), which have the ability to resist fatigue, but contract at a slower rate and generate lower forces, high intensity interval training will improve your ability to achieve and sustain prolonged maximal efforts by utilising mainly type-II fibres. Therefore, despite our own genetic disposition, correct training can increase the effectiveness of our physiological systems, in particular our muscular function and strength, whatever our muscular composition.
Training
Interval sessions to improve sprint performance should attempt to replicate the racing situation as closely as possible. When you're out on a training ride, try to incorporate 10-12 20-second sprints. Typically, warm-up for 20 minutes and then set targets along the road side. At predetermined points, sprint as if you were in a racing situation, recover sufficiently and repeat. Ideally, attempt this when out with the chain gang and use them as a base to sprint from. This will sharpen your own skills and give you the confidence to jump away from the group. Remember to tell the group what your plans are though, so as not to upset others. For the novice performer, integrate this type of training into one session a week; for those more experienced, two or three times will assist you with your sprint development.
But sprinting on the bike is not just about pure muscular strength. The proper techniques will ensure that you make the most of your developing strength and power and ensure that the forces being generated are going through the bike to produce forward momentum. Typically in the road race, a sprint is not just required at the end - repeated efforts throughout are a necessity if you are going to ensure you are at the front to contest for the line, therefore you need to be fit enough to get to the finish!
Good technique is very important and is the deciding factor in most sprinting situations.
Choosing the correct gear is vital to ensure quick acceleration. Faster cadences will generally allow for such changes of pace, but may limit top end speed, so experiment when out on the bike. Also watch the pro riders and study their position.
Tactics
Finally, the most important technical aspect of sprinting is tactics. When you are in another riders' slipstream you are saving vital energy reserves. By coming from behind the leading rider, they will not know when you are going to make your attack and therefore you will already be at an advantage. A further important component is knowledge, both of the course and of other competitors.
Having an understanding of the course will provide you with an advantage even before the race begins.
When inspecting it, ask yourself questions such as, where is the finish? What is the road gradient like? Are there any bends or obstacles? Are there any distinguishing features towards the end that will remind me of the approaching line? What direction is the wind coming from? If it's a headwind will I struggle if I start my sprint off too early, or if it's a tailwind could I surprise the group and attack further back down the road? Examine the start sheet when you sign on as well - knowing who's riding will assist you when deciding which wheel to follow during the final moments. Having competed in a series of local road races.
I remember a strong rider who always appeared in the top three positions every races I competed in. In the final race of the series, I decided that if it again came down to a sprint finish, I would be the one following the rider's wheel. With a mile to go, I worked my way up through the bunch; using my knowledge of race tactics, the course, and the other competitors, I found his wheel. Pulling me up towards the line, I chose my moment, made my attack and won the race!