@kellynoelharman here is a screen shot of my sprints in 3 different scenarios. As you can see, the power shoots up very quickly. Being able to sprint like this is a function of the following:
- Quick shifting to the gear that provides the right amount of resistance to be able to accelerate quickly and forcefully when sprinting
- High cadence while sprinting
- Shifting mid-sprint as needed to keep tension in the chain for the whole sprint
- Proper body position - hands in the drops, chest over the handle bars, pushing down and pulling up on the pedals
- Being able to generate high power and high torque
I must mention that Rider Type plays a role here too. I am an explosive rider, so my fast-twitch muscles provide an extra advantage. To give you an idea, I am able to get up to my max power in 2-3 seconds from the start of the sprint (you can see my power is like a straight line up). Not everyone is like that. Slow-twitch dominant riders take a bit longer to ramp up, but are usually able to hold that top power longer. Strength training has helped me being able to sustain the power longer for the duration of the sprint- because my tendency is to shoot up high fast then fade.
But regardless of Rider Type, everyone can improve their sprints by practicing the techniques mentioned above and by developing their top-end power in workouts.
Scenario 1: from a 4 min effort at low threshold (about 95% of FTP):
Scenario 2: from speed at lower power
Scenario 3: from a stop with one foot on the ground (race starts)