As a rule, you only ever find sprinters at one end of the peloton. In the mountains they hang off the back of the bunch in the gruppetto or autobus, grimly crawling up each climb with the sole aim of finishing inside the time limit to fight another day. On flat stages, however, they will be right at the front of the pack, ducking and diving at speeds in excess of 60kph in search of glory.
Sprinters excel in explosive accelerations in bunch sprints at the end of flat stages. There is no one physical template for the modern sprinter. They range from the diminutive Mark Cavendish to the imposing Andre Greipel to the lanky six-foot-four frame of Tom Boonen. What they have in common is the ability to call upon fast-twitch muscle to produce short bursts of prodigious power (Greipel can produce an impressive 2,000 watts), combined with the ability to spot a gap and the bravery to throw themselves into it in the hurly-burly that is the last 30 seconds of a bunch sprint.

World champion Cavendish is the fastest pure sprinter of recent years (image courtesy of Roxanne King)
There are, however, three distinct types of sprinter.
‘Pure’ sprinters such as Cavendish and Greipel struggle to keep up with the peloton on even relatively moderate hills. This means they can only win on flat stage profiles, but the best pure sprinters also tend to possess the most savage ‘jumps’ of acceleration which allow them to overtake their rivals.
Just as importantly, a good jump prevents a following rider from taking their wheel and gaining the aerodynamic benefit of sitting in the ‘hole’ in the air that exists immediately behind every rider.
Others, such as Peter Sagan, Thor Hushovd or Boonen, have more of a balance of strength and speed. This allows them to stay in touch over hilly stages and put them in position to contend for victory on a rolling Classics-style stage, or one with an uphill finish. This ability can be particularly useful for points jersey contenders, who can gain intermediate bonus points in the mountains which the pure sprinters cannot.
Power sprinters are often just as fast as the pure sprinters, but may not have quite the same instant acceleration on a flat finish.
One final category of sprinter is the lead-out man. These are generally fine sprinters in their own right, but they are detailed to provide the lead-out for their team’s main sprinter. Geraint Thomas (and before him Mark Renshaw, now with Rabobank) have fulfilled this role with distinction for Cavendish.
They are responsible for piloting their man into the right position in the final kilometre before opening up their sprint with 400-500 metres to go, with the aim of serving as a slingshot out of which their main sprinter can propel himself as they peel away, spent, with typically 200 metres to go. A good lead-out man is not just fast, but also possesses exemplary timing and positional instinct to arrive in the right place at the right time.