Well, each race is its own individual event, but average for a Cat-5 crit? Probably more in the 24.5--25mph range. Add another 1/2mph for each level up, to Pro/1-2's who maybe average 28+ for a crit. And the more prestigious the race, the faster the speeds.

However--and this is a BIG however--it's not the average speeds that matter in crits. It's the accelerations: they'll kill you. Cat-5's have no problem going from 18-19mph as they sit around watching each other, and then reacting to a rider or two trying to break away at 28+mph. Pros go from 27-28mph, accelerate to 32-33mph and then recover at 28. It's very hard. Then there's the accelerations out of corners. A 4-corner crit for 30-minutes on a 1-mile course? Easily hitting 40-60 corners per race. That's alot of accelerations & recoveries.

As for sprinting? Wow, that's all over, too. For Cat-5's, maybe 35mph to begin with. Regional pro's easily best 40mph, with World Tour sprinters/International Track sprinters beating 42+mph (70kph). (Our local Saturday Training Ride, which attracts regional pros, cat-1's etc, and retired Olympians & World Tour riders has a sprint, a downhill false-flat where they'll hit 42--44mph.)