Three sprint workouts that I do may be of interest to some. For long sprints I'm in the saddle riding at 450 - 500 watts for 45 seconds then jump OTS and sprint while dropping gears and keeping 900+ watts for 15". Those suckers really hurt the last 20-25 seconds.
Another is to be riding at Z2 and 90 rpm then go OTS in the same gear and push/pull the pedals with everything for 12 full pedal rotations. Do this one on the minute for 5 sets of 6 reps.
Find a 4 to 5% hill leading onto a 300 meter flat. Ride down the hill at 28 to 30 mph and carry the speed onto the flat. Once on the flat go OTS and sprint for 20".
I do all my OTS sprinting in the drops with my nose as close to bar height as possible.